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Javadiyan S, Craig JE, Souzeau E, Sharma S, Lower KM, Mackey DA, Staffieri SE, Elder JE, Taranath D, Straga T, Black J, Pater J, Casey T, Hewitt AW, Burdon KP. High-Throughput Genetic Screening of 51 Pediatric Cataract Genes Identifies Causative Mutations in Inherited Pediatric Cataract in South Eastern Australia. G3 (Bethesda) 2017; 7:3257-3268. [PMID: 28839118 PMCID: PMC5633377 DOI: 10.1534/g3.117.300109] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 08/15/2017] [Indexed: 01/09/2023]
Abstract
Pediatric cataract is a leading cause of childhood blindness. This study aimed to determine the genetic cause of pediatric cataract in Australian families by screening known disease-associated genes using massively parallel sequencing technology. We sequenced 51 previously reported pediatric cataract genes in 33 affected individuals with a family history (cases with previously known or published mutations were excluded) using the Ion Torrent Personal Genome Machine. Variants were prioritized for validation if they were predicted to alter the protein sequence and were absent or rare with minor allele frequency <1% in public databases. Confirmed mutations were assessed for segregation with the phenotype in all available family members. All identified novel or previously reported cataract-causing mutations were screened in 326 unrelated Australian controls. We detected 11 novel mutations in GJA3, GJA8, CRYAA, CRYBB2, CRYGS, CRYGA, GCNT2, CRYGA, and MIP; and three previously reported cataract-causing mutations in GJA8, CRYAA, and CRYBB2 The most commonly mutated genes were those coding for gap junctions and crystallin proteins. Including previous reports of pediatric cataract-associated mutations in our Australian cohort, known genes account for >60% of familial pediatric cataract in Australia, indicating that still more causative genes remain to be identified.
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Affiliation(s)
- Shari Javadiyan
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - Jamie E Craig
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - Emmanuelle Souzeau
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - Shiwani Sharma
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - Karen M Lower
- Department of Haematology and Genetic Pathology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - David A Mackey
- Centre for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, Western Australia 6009, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria 3002, Australia
- Department of Surgery, University of Melbourne, Victoria 3010, Australia
| | - Sandra E Staffieri
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria 3002, Australia
- Department of Surgery, University of Melbourne, Victoria 3010, Australia
- Department of Ophthalmology, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
| | - James E Elder
- Department of Surgery, University of Melbourne, Victoria 3010, Australia
- Department of Ophthalmology, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
| | - Deepa Taranath
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - Tania Straga
- Ophthalmology Department, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia
| | - Joanna Black
- Ophthalmology Department, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia
| | - John Pater
- Ophthalmology Department, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia
| | - Theresa Casey
- Ophthalmology Department, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia
| | - Alex W Hewitt
- Department of Surgery, University of Melbourne, Victoria 3010, Australia
- Ophthalmology Department, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia
- Department of Paediatrics, University of Melbourne, Victoria 3010, Australia
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Kathryn P Burdon
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7000, Australia
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Irum B, Khan SY, Ali M, Daud M, Kabir F, Rauf B, Fatima F, Iqbal H, Khan AO, Al Obaisi S, Naeem MA, Nasir IA, Khan SN, Husnain T, Riazuddin S, Akram J, Eghrari AO, Riazuddin SA. Deletion at the GCNT2 Locus Causes Autosomal Recessive Congenital Cataracts. PLoS One 2016; 11:e0167562. [PMID: 27936067 PMCID: PMC5147899 DOI: 10.1371/journal.pone.0167562] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 11/16/2016] [Indexed: 11/25/2022] Open
Abstract
PURPOSE The aim of this study is to identify the molecular basis of autosomal recessive congenital cataracts (arCC) in a large consanguineous pedigree. METHODS All participating individuals underwent a detailed ophthalmic examination. Each patient's medical history, particularly of cataracts and other ocular abnormalities, was compiled from available medical records and interviews with family elders. Blood samples were donated by all participating family members and used to extract genomic DNA. Genetic analysis was performed to rule out linkage to known arCC loci and genes. Whole-exome sequencing libraries were prepared and paired-end sequenced. A large deletion was found that segregated with arCC in the family, and chromosome walking was conducted to estimate the proximal and distal boundaries of the deletion mutation. RESULTS Exclusion and linkage analysis suggested linkage to a region of chromosome 6p24 harboring GCNT2 (glucosaminyl (N-acetyl) transferase 2) with a two-point logarithm of odds score of 5.78. PCR amplifications of the coding exons of GCNT2 failed in individuals with arCC, and whole-exome data analysis revealed a large deletion on chromosome 6p in the region harboring GCNT2. Chromosomal walking using multiple primer pairs delineated the extent of the deletion to approximately 190 kb. Interestingly, a failure to amplify a junctional fragment of the deletion break strongly suggests an insertion in addition to the large deletion. CONCLUSION Here, we report a novel insertion/deletion mutation at the GCNT2 locus that is responsible for congenital cataracts in a large consanguineous family.
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Affiliation(s)
- Bushra Irum
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shahid Y. Khan
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Muhammad Ali
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Muhammad Daud
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Firoz Kabir
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Bushra Rauf
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Fareeha Fatima
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Hira Iqbal
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Arif O. Khan
- King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
| | - Saif Al Obaisi
- King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
| | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Idrees A. Nasir
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shaheen N. Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Tayyab Husnain
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan
- National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan
- National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Allen O. Eghrari
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
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Viswanathan K, Narang S, Hinderlich S, Lee YC, Betenbaugh MJ. Engineering intracellular CMP-sialic acid metabolism into insect cells and methods to enhance its generation. Biochemistry 2005; 44:7526-34. [PMID: 15895995 DOI: 10.1021/bi047477y] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous studies have reported that insect cell lines lack the capacity to generate endogenously the nucleotide sugar, CMP-Neu5Ac, required for sialylation of glycoconjugates. In this study, the biosynthesis of this activated form of sialic acid completely from endogenous metabolites is demonstrated for the first time in insect cells by expressing the mammalian genes required for the multistep conversion of endogenous UDP-GlcNAc to CMP-Neu5Ac. The genes for UDP-GlcNAc-2-epimerase/ManNAc kinase (EK), sialic acid 9-phosphate synthase (SAS), and CMP-sialic acid synthetase (CSAS) were coexpressed in insect cells using baculovirus expression vectors, but the CMP-Neu5Ac and precursor Neu5Ac levels synthesized were found to be lower than those achieved with ManNAc supplementation due to feedback inhibition of the EK enzyme by CMP-Neu5Ac. When sialuria-like mutant EK genes, in which the site for feedback regulation has been mutated, were used, CMP-Neu5Ac was synthesized at levels more than 4 times higher than that achieved with the wild-type EK and 2.5 times higher than that achieved with ManNAc feeding. Addition of N-acetylglucosamine (GlcNAc), a precursor for UDP-GlcNAc, to the media increased the levels of CMP-Neu5Ac even more to a level 7.5 times higher than that achieved with ManNAc supplementation, creating a bottleneck in the conversion of Neu5Ac to CMP-Neu5Ac at higher levels of UDP-GlcNAc. The present study provides a useful biochemical strategy to synthesize and enhance the levels of the sialylation donor molecule, CMP-Neu5Ac, a critical limiting substrate for the generation of complex glycoproteins in insect cells and other cell culture systems.
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Affiliation(s)
- Karthik Viswanathan
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
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Abstract
Capsular polysaccharides (CPs) of several pathogenic bacteria are thought to be good materials for the development of new therapeutic reagents. These polysaccharides can be used as vaccines against infection of pathogenic bacteria and are also useful as inhibitors for disease caused by aberrant and abnormal cell-cell interaction, such as cancer metastasis and inflammation. Since bacterial CPs are diverse in structure and these bacteria have a variety of sugar transferases responsible for the synthesis of CPs, bacterial CP synthesis (cps) genes have attracted much interest as a source of glycosyltransferases useful for glycoengineering. In this review, we describe physiological effects of the bacterial CPs on mammalian cells, and the structure and function of the cps genes, by focusing on group B streptococci, Streptococcus agalactiae type Ia and Ib, that produce high-molecular weight polysaccharides consisting of the following pentasaccharide repeating units: -->4)-[alpha-D-NeupNAc-(2-->3)-beta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1-->3)]-beta-D-Galp-(1-->4)-beta-D-Glcp-(1--> and -->4)-[alpha-D-NeupNAc-(2-->3)-beta-D-Galp-(1-->3)-beta-D-GlcpNAc-(1-->3)]-beta-D-Galp-(1-->4)beta-D-Glcp-(1-->, respectively.
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Affiliation(s)
- Katsuhide Miyake
- Research Center for Advanced Waste and Emission Management, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
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Mathysen D, Wuyts W, Bossuyt PJ, Wauters JG, Van Hul W. Assignment of the mouse Extl1 gene to the distal part of chromosome 4 by in situ hybridization and radiation hybrid mapping. Cytogenet Cell Genet 2001; 92:162-3. [PMID: 11306818 DOI: 10.1159/000056890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- D Mathysen
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
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Abstract
Human EXTL2 is an alpha1,4-N-acetylhexosaminyltransferase involved in the biosynthesis of heparin/heparan sulfate. We have cloned and characterized the mouse homolog of this gene. Mouse Extl2 encodes a 330 amino acid protein that is 87% identical to its human counterpart. Expression analysis showed that Extl2 is ubiquitously expressed in adult mouse tissues and that the Extl2 transcript is already present in early stages of embryonic development. Determination of the genomic structure revealed that the Extl2 gene spans five exons within a 10-kb region and that the genomic organization between mouse and man is well preserved, with conservation of the number and position of all five exons. By radiation hybrid analysis, Extl2 was mapped to mouse chromosome 3, in a region homologous to the human EXTL2 region on chromosome 1.
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Affiliation(s)
- W Wuyts
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
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Abstract
Hereditary multiple exostoses (HME) is a genetically heterogeneous disease characterized by the development of bony protuberances at the ends of all long bones. Genetic analyses have revealed HME to be a multigenic disorder linked to three loci on chromosomes 8q24 (EXT1), 11p11-13 (EXT2), and 19p (EXT3). The EXT1 and EXT2 genes have been cloned and defined as glycosyltransferases involved in the synthesis of heparan sulfate. EST database analysis has demonstrated additional gene family members, EXT-like genes (EXTL1, EXTL2, and EXTL3), not associated with a HME locus. The mouse homologs of EXT1 and EXT2 have also been cloned and shown to be 99% and 95% identical to their human counterparts, respectively. Here, we report the identification of the mouse EXTL1 gene and show it is 74% identical to the human EXTL1 gene. Expression studies of all three mouse EXT genes throughout various stages of embryonic development were carried out and whole-mount in situ hybridization in the developing limb buds showed high levels of expression of all three EXT genes. However, in situ hybridization of sectioned embryos revealed remarkable differences in expression profiles of EXT1, EXT2, and EXTL1. The identical expression patterns found for the EXT1 and EXT2 genes support the recent observation that both proteins form a glycosyltransferase complex. We suggest a model for exostoses formation based on the involvement of EXT1 and EXT2 in the Indian hedgehog/parathyroid hormone-related peptide (PTHrP) signaling pathway, an important regulator of the chondrocyte maturation process.
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Affiliation(s)
- D Stickens
- McDermott Center for Human Growth and Development, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75235-8591, USA.
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Kitagawa H, Sugahara K. [Biosynthesis of heparan sulfate and the tumor suppressor EXT gene family]. Tanpakushitsu Kakusan Koso 2000; 45:579-86. [PMID: 10714174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Affiliation(s)
- H Kitagawa
- Department of Biochemistry, Kobe Pharmaceutical University, Japan.
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Wuyts W, Spieker N, Van Roy N, De Boulle K, De Paepe A, Willems PJ, Van Hul W, Versteeg R, Speleman F. Refined physical mapping and genomic structure of the EXTL1 gene. Cytogenet Cell Genet 1999; 86:267-70. [PMID: 10575224 DOI: 10.1159/000015317] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recently, the EXTL1 gene, a member of the EXT tumor suppressor gene family, has been mapped to 1p36, a chromosome region which is frequently implicated in a wide variety of malignancies, including breast carcinoma, colorectal cancer and neuroblastoma. In this study, we show that the EXTL1 gene is located between the genetic markers D1S511 and D1S234 within 200 kb of the LAP18 gene on chromosome 1p36. 1, a region which has been proposed to harbor a tumor suppressor gene implicated in MYCN-amplified neuroblastomas. In addition, we determined the genomic structure of the EXTL1 gene, revealing that the EXTL1 coding sequence spans 11 exons within a 50-kb region.
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Affiliation(s)
- W Wuyts
- Department of Medical Genetics, University of Antwerp, Belgium.
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Abstract
Hereditary multiple exostoses (EXT; MIM 133700) is an autosomal dominant bone disorder. It is genetically heterogeneous with at least three chromosomal loci: EXT1 on 8q24.1, EXT2 on 11p11, and EXT3 on 19p. EXT1 and EXT2, the two genes responsible for EXT1 and EXT2, respectively, have been cloned. Recently, three other members of the EXT gene family, named the EXT-like genes (EXTL: EXTL1, EXTL2, and EXTL3), have been isolated. EXT1, EXT2, and the three EXTLs are homologous with one another. We have identified the intron-exon boundaries of EXTL1 and EXTL3 and analyzed EXT1, EXT2, EXTL1, and EXTL3, in 36 Chinese families with EXT, to identify underlying disease-related mutations in the Chinese population. Of the 36 families, five and 12 family groups have mutations in EXT1 and EXT2, respectively. No disease-related mutation has been found in either EXTL1 or EXTL2, although one polymorphism has been detected in EXTL1. Of the 15 different mutations (three families share a common mutation in EXT2), 12 are novel. Most of the mutations are either frameshift or nonsense mutations (12/15). These mutations lead directly or indirectly to premature stop codons, and the mutations generate truncated proteins. This finding is consistent with the hypothesis that the development of EXT is mainly attributable to loss of gene function. Missense mutations are rare in our families, but these mutations may reflect some functionally crucial regions of these proteins. EXT1 is the most frequent single cause of EXT in the Caucasian population in Europe and North America. It accounts for about 40% of cases of EXT. Our study of 36 EXT Chinese families has found that EXT1 seems much less common in the Chinese population, although the frequency of the EXT2 mutation is similar in the Caucasian and Chinese populations. Our findings suggest a possibly different genetic spectrum of this disease in different populations.
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Affiliation(s)
- L Xu
- National Laboratory of Medical Genetics, Hunan Medical University, Changsha, PR China
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Kitagawa H, Shimakawa H, Sugahara K. The tumor suppressor EXT-like gene EXTL2 encodes an alpha1, 4-N-acetylhexosaminyltransferase that transfers N-acetylgalactosamine and N-acetylglucosamine to the common glycosaminoglycan-protein linkage region. The key enzyme for the chain initiation of heparan sulfate. J Biol Chem 1999; 274:13933-7. [PMID: 10318803 DOI: 10.1074/jbc.274.20.13933] [Citation(s) in RCA: 163] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously demonstrated a unique alpha-N-acetylgalactosaminyltransferase that transferred N-acetylgalactosamine (GalNAc) to the tetrasaccharide-serine, GlcAbeta1-3Galbeta1-3Galbeta1-4Xylbeta1-O-Ser (GlcA represents glucuronic acid), derived from the common glycosaminoglycan-protein linkage region, through an alpha1,4-linkage. In this study, we purified the enzyme from the serum-free culture medium of a human sarcoma cell line. Peptide sequence analysis of the purified enzyme revealed 100% identity to the multiple exostoses-like gene EXTL2/EXTR2, a member of the hereditary multiple exostoses (EXT) gene family of tumor suppressors. The expression of a soluble recombinant form of the protein produced an active enzyme, which transferred alpha-GalNAc from UDP-[3H]GalNAc to various acceptor substrates including GlcAbeta1-3Galbeta1-3Galbeta1-4Xylbeta1-O-Ser. Interestingly, the enzyme also catalyzed the transfer of N-acetylglucosamine (GlcNAc) from UDP-[3H]GlcNAc to GlcAbeta1-3Galbeta1-O-naphthalenemethanol, which was the acceptor substrate for the previously described GlcNAc transferase I involved in the biosynthetic initiation of heparan sulfate. The GlcNAc transferase reaction product was sensitive to the action of heparitinase I, establishing the identity of the enzyme to be alpha1, 4-GlcNAc transferase. These results altogether indicate that EXTL2/EXTR2 encodes the alpha1,4-N-acetylhexosaminyltransferase that transfers GalNAc/GlcNAc to the tetrasaccharide representing the common glycosaminoglycan-protein linkage region and that is most likely the critical enzyme that determines and initiates the heparin/heparan sulfate synthesis, separating it from the chondroitin sulfate/dermatan sulfate synthesis.
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Affiliation(s)
- H Kitagawa
- Department of Biochemistry, Kobe Pharmaceutical University, Higashinada-ku, Kobe 658-8558, Japan
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