Identification of base substitutions in ten types of rare variants of phosphoglucomutase-1 (PGM1) encountered in Japanese

Molecular aspects of biochemical markers

This review summarizes present knowledge of the molecular basis for certain serum protein and red cell enzyme markers that have played important roles in forensic individualization and paternity tests. Most genes have nucleotide variations at two or more mutations sites, and their alleles exist as haplotypes. Allelic diversity is generated by various mechanisms including point mutation, intragenic recombination, gene conversion, and alternative splicing. Deficient and null alleles arise from point mutation and deletion. The value of genomic information on allelic diversity is also discussed.

Regulation of phosphoglucomutase 1 phosphorylation and activity by a signaling kinase

We have identified a novel mechanism of cross-talk between cell signaling and metabolic pathways, whereby the signaling kinase p21-activated kinase 1 (Pak1) binds to, phosphorylates and enhances the enzymatic activity of phosphoglucomutase 1 (PGM), an important regulatory enzyme in cellular glucose utilization and energy homeostasis. Pak1 and PGM were colocalized in model cell systems and showed functional interactions in a physiological setting. Strong direct interaction of PGM with Pak1 but not Pak2, Pak3, or Pak4 was observed. PGM binding was within 75-149 amino acids (aa) of Pak1, while Pak1 binding to PGM was in the N-terminal 96 aa. Pak1-mediated phosphorylation of PGM selectively on threonine 466 significantly increased PGM enzymatic activity and could be blocked by transfection with a dominant-negative Pak1 expression vector and by Pak1-specific small inhibitory RNA. Stable transfection of PGM into PGM-deficient K562 leukemia cells further demonstrated the role of Pak1 in regulating PGM activity. The results presented here provide new evidence that the cell signaling kinase Pak1 is a novel regulator of glucose metabolism through its phosphorylation and regulation of PGM activity. These findings suggest a new mechanism whereby growth factor signaling may coordinately integrate metabolic regulation with established signaling functions of cell cycle regulation and cell growth.