Phosphorylation mapping of Laminin b1-chain: Kinases in association with active sites

ABSTRACT

Laminins are a major constituent of the extracellular matrix (ECM). Laminin-111, the most extensively studied lamininisoform, consists of the a1, the b1 and the c1 chain, and is involved in many cellular processes, like adhesion, migrationand differentiation. Given the regulatory role of phosphorylation in protein function, it is important to identify thephosphorylation sites of human laminin b1-chain sequence (LAMB1). Therefore, we computationally predicted all possiblephosphorylation sites in LAMB1. For the first time, we identified the possibly responsible kinases foralready in vitro experimentally observed phosphorylated residues in LAMB1. All known functional (active) sites ofLAMB1, were recorded after an extensive literature search and combined with the experimentally observed and ourpredicted phosphorylated residues. This generated a detailed phosphorylation map of LAMB1. Five kinases (PKA, PKC,CKII, CKI and GPCR1) were indicated important, while the role of PKA, PKC and CKII, kinases known for ectophosphorylation activity, was highlighted. The activity of PKA and PKC was associated with the active site RIQNLLKITNLRIKFVKLHTLGDNLLDS. Also, predicted phosphorylations inside two amyloidogenic (DSITKYFQMSLE,VILQHSAADIAR) and two anti-cancerous (YIGSR and PDSGR) sites suggested a possible role in the development of thecorresponding diseases.