GlcNAcylation of the Unique domain of Lyn A protein of the Src family

Abstract

Lyn is a protein member of the Src family of non-receptor tyrosine kinases (SFK). These proteins are involved in cell signalling pathways related to cell growth, migration, invasion, and survival. Lyn mediates the induction of apoptosis. Lyn tyrosine kinase exists as two isoforms, Lyn A and Lyn B of 56 and 53 kDa, respectively. These isoforms differ by a 21-aa insert found in the N-terminal unique domain of Lyn A. In this research, the whole protein Lyn A will not be studied, the focus will be on the Unique and SH3 domain. O-GlcNAcylation is a post-translational modification that involves the attachment of single O-linked N-acetylglucosamine (O-GlcNAc) moieties to Ser and Thr residues of cytoplasmic, nuclear and mitochondrial proteins, by an enzymatic reaction with OGT enzyme. Phosphorylation can also target Ser and Thr residues, then, between O-GlcNAcylation and phosphorylation exists and intensive and complex interplay. O-GlcNAcylation has been proposed to function as a nutrient and stress sensor that regulates cellular processes. In this research, the O-GlcNAcylation of Lyn A will be studied by performing an enzymatic linked assay of NADH/NAD+. To do so, USH3LynA protein and OGT enzyme will be expressed by E. coli and purified