Evidence for age-related deamidation reactions in erythrocyte p55 and glycophorins C and D: implications for signal transduction involving tumour-suppressor proteins in higher eukaryotes

Abstract 

The methylation of erythrocyte cytoskeletal proteins by methyltransferases is a strategy for the repair of deamidated asparagine residues. Evidence from extant data shows that the junction point proteins of the erythrocyte cytoskeleton, band 3, ankyrin, glycophorins C/D, band 4.1, calmodulin, and p55 are all methylated in situ. It is suggested that sequence-dependent deamidation of asparagine residues in p55, 4.1 and glycophorins C/D could affect the interactions of these junction point proteins in an age-dependent manner. Comparison of the asparagine content of 4.1 binding regions of p55 analogues dig and hdlg acts as a caveat to the extrapolation of findings made in erythrocytes to other eukaryotic cells, and has important implications for transmembrane signalling pathways and age-dependent changes in the membrane-binding characteristics of tumour-suppressor proteins in higher cell systems.

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