Srm

Src-related kinase lacking C-terminal regulatory tyrosine and N-terminal myristoylation sites (SRMS/Srm) is a nonreceptor tyrosine kinase with SH3, SH2, and kinase domains, but it lacks the N-terminal myristoylation glycine and C-terminal inhibitory tyrosine typical of Src-family regulation^[1]. Mechanistically, SRMS belongs to the Brk-family kinase group with Brk/PTK6 and Frk, whose conserved exon structure distinguishes them from c-Src and Fyn^[2]. Compared with these related isoforms, SRMS shows a distinctive extended N-terminal region, constitutive activity in ectopic-expression systems, and N-terminal control of enzymatic activity and DOK1 phosphorylation^[3]. Phosphoproteomics further linked SRMS to candidate substrates and signaling processes involving protein ubiquitination, mitotic cell cycle, energy metabolism, RNA processing, Wnt signaling, and TNF signaling^[4]. In disease models, SRMS inhibited autophagy by phosphorylating FKBP51, sustained AKT activation, promoted cancer growth, and showed kinase-dependent sensitivity to ibrutinib-mediated inhibition^[5]. SRMS also phosphorylated the C terminus of BRK, but not SRC, supporting isoform-specific kinase regulation within related intracellular tyrosine kinase networks^[6].