Characterization of human red cell Rh (rhesus-)specific polypeptides by limited proteolysis

A triple action chemosensor for Cu2+by chromogenic, Cr3+by fluorogenic and CN−by relay recognition methods with bio-imaging of HeLa cells

A rhodamine-B based triple action chemosensor has been developed with recycling ability, and its application towards bio-imaging of HeLa cells is studied. It selectively senses Cu²⁺, Cr³⁺and CN⁻ions in aqueous medium.

Biochemical aspects of the blood group Rh (rhesus) antigens

Despite their importance in clinical haematology, the details of the structures and possible functions of the proteins associated with Rh antigen expression have only recently begun to emerge. The antigens are carried by a multimeric complex between a M(r) 30,000 polypeptide which is not glycosylated (the Rh30 polypeptide), and a heavily glycosylated glycoprotein (the Rh50 glycoprotein). The N-terminal amino acid sequences of the two types of proteins were determined and used to isolated cDNA clones. The Rh30 and Rh50 proteins are both very hydrophobic membrane proteins, each containing up to 12 membrane spans. The two proteins are homologous in sequence and clearly belong to the same family. They are erythroid-specific and not related to any other known family of proteins. The Rh30 polypeptides are the genetic determinants of Rh blood group antigen activity. One polypeptide (Rh30A) is probably associated with CcEe antigen activity, while another (Rh30B) is responsible for the D antigen. The proteins have structures typical of transporters but their functions are still unclear. A number of other red cell membrane proteins (LW, CD47, glycophorin B and Fy) show alterations in red cells lacking Rh antigens (Rhnull). These proteins may have a role in the biosynthesis or function of the Rh30 and Rh50 proteins.

Molecular cloning and primary structure of the human blood group RhD polypeptide

The RH (rhesus) blood group locus from RhD-positive donors is composed of two homologous structural genes, one of which encodes the Cc and Ee polypeptides, whereas the other, which is missing in the RhD-negative condition, encodes the D protein that carries the major antigen of the RH system. Recently, different splicing isoforms transcribed from the CcEe gene were isolated. We report now the characterization of two other Rh clones, RhII and RhXIII, generated by alternative choices for poly(A) addition sites that were identified as the RhD gene transcripts. That these cDNAs represented the RhD messenger and that the previously described Rh clones were derived from the CcEe gene was demonstrated by amplification of RhII/XIII sequences only from D-positive genomes and by cloning and sequencing of D- and CcEe-specific gene fragments. The predicted translation product of the RhD mRNA is a 417-amino acid protein (M(r) = 45,500) that exhibited a similar membrane organization with 13 bilayer-spanning domains compared with the polypeptide encoded by the CcEe gene. The D and Cc/Ee polypeptides differ by 36 amino acid substitutions (8.4% divergence), but the NH2- and COOH-terminal regions of the two proteins are well conserved. Similarly, five of the six cysteine residues of the Cc/Ee proteins were conserved in the D protein, including the unique exofacial cysteine, which is critical for antigenic reactivity. The sequence homology between the Cc/Ee and D proteins supports the concept that the genes encoding these polypeptides have evolved by duplication of a common ancestor gene.

Isolation and partial characterization of the human erythrocyte band 7 integral membrane protein

Monoclonal antibodies to the Mr 31,000 major integral membrane protein of the human erythrocyte band 7 region were used to identify the corresponding polypeptide chain and epitope-carrying fragments on immunoblots. Analysis of the erythrocyte membrane, membrane fractions, and cytosol revealed that the Mr 31,000 band 7 integral membrane protein is unique and not related to any of the other water-soluble or membrane-bound band 7 components. Cross-reacting proteins were identified in the membranes of other mammalian erythrocytes and in cell lines of epithelial and lymphoid origin. Proteolytic digestion of intact human erythrocytes or erythrocyte membranes demonstrated that the band 7 integral membrane protein has an intracellular domain larger than Mr 12,000; it does not have an extracellular one. One of the monoclonal antibodies was employed for the isolation of band 7 integral membrane protein by immunoaffinity chromatography; subsequent Edman degradation revealed a blocked N-terminus.

Regulator genes affecting red cell antigens

Several mechanisms may be involved to explain the action of genes that regulate the expression of red cell antigens. When carbohydrate antigens are involved, lack of an enzyme in the biochemical pathway prevents formation of the precursor for the next and following steps of that path, or, alternatively, addition of an extra sugar to the immuno-dominant sugar may produce a new structure in which the expression of the expected antigen is masked. Thinking of genetic rather than biochemical interference, a regulator gene may "switch-off" the action of a structural gene, and this mechanism could involve the upset of repressor and/or derepressor genes. The mechanisms for the regulator genes described in this article are unknown. The effect of XGR is limited to red cells: the expression of 12E7 antigen on other tissues and cells, other than red cells, is invariable. The reported effects of XOr and XQ are for red cells, but it is unlikely that other cells and tissues have been studied intensively; propositi with these regulator genes are much rarer than people informative for XGR and In(Lu). The effects of In(Lu) are not limited to red cells but have been shown to regulate the expression of p80 on some white cells. Most of the abnormalities in Rhnull cells appear to be associated with the lack of the Rh antigens and lack of Rh proteins. The hypothesis of a functional complex involving Rh, lack of which affects incorporation of apparently unrelated proteins into the red cell membrane, is an attractive idea. Studies of the similar phenotype, Rhmod, suggest that some Rh specificities can be present in cells that appear to be as abnormal, serologically and morphologically, as Rhnull cells. Perhaps some polypeptides are functionally more important than others and perhaps all polypeptides required for the functional efficiency of the Rh complex have not yet been identified. Lack of Lutheran antigens is not always accompanied by modification of other red cell antigens. As suggested by Telen and green, if In(Lu) acts via a single mechanism, then that mechanism differs from that of XS2. Certainly the mechanisms of In(Lu) and XS2 differ in their action on the expression of CD44 or p80 antigens. The red cell surface is well charted territory, familiar to serologists, immunologists, biochemists, and geneticists. It still provides an excellent model for study of cell surface antigens and for the regulator genes described above that modify expression of some red cell antigens.(ABSTRACT TRUNCATED AT 400 WORDS)