1k9a
Crystal structure analysis of full-length carboxyl-terminal Src kinase at 2.5 A resolution
Structural highlights
FunctionCSK_RAT Non-receptor tyrosine-protein kinase that plays an important role in the regulation of cell growth, differentiation, migration and immune response. Phosphorylates tyrosine residues located in the C-terminal tails of Src-family kinases (SFKs) including LCK, SRC, HCK, FYN, LYN or YES1. Upon tail phosphorylation, Src-family members engage in intramolecular interactions between the phosphotyrosine tail and the SH2 domain that result in an inactive conformation. To inhibit SFKs, CSK is recruited to the plasma membrane via binding to transmembrane proteins or adapter proteins located near the plasma membrane. Suppresses signaling by various surface receptors, including T-cell receptor (TCR) and B-cell receptor (BCR) by phosphorylating and maintaining inactive several positive effectors such as FYN or LCK (By similarity).[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe carboxyl-terminal Src kinase (Csk) is an indispensable negative regulator for the Src family tyrosine kinases (SFKs) that play pivotal roles in various cell signalings. To understand the molecular basis of the Csk-mediated regulation of SFKs, we elucidated the crystal structure of full-length Csk. The Csk crystal consists of six molecules classified as active or inactive states according to the coordinations of catalytic residues. Csk assembles the SH2 and SH3 domains differently from inactive SFKs, and their binding pockets are oriented outward enabling the intermolecular interaction. In active molecules, the SH2-kinase and SH2-SH3 linkers are tightly stuck to the N-lobe of the kinase domain to stabilize the active conformation, and there is a direct linkage between the SH2 and the kinase domains. In inactive molecules, the SH2 domains are rotated destroying the linkage to the kinase domain. Cross-correlation matrices for the active molecules reveal that the SH2 domain and the N-lobe of the kinase domain move as a unit. These observations suggest that Csk can be regulated through coupling of the SH2 and kinase domains and that Csk provides a novel built-in activation mechanism for cytoplasmic tyrosine kinases. Structure of the carboxyl-terminal Src kinase, Csk.,Ogawa A, Takayama Y, Sakai H, Chong KT, Takeuchi S, Nakagawa A, Nada S, Okada M, Tsukihara T J Biol Chem. 2002 Apr 26;277(17):14351-4. Epub 2002 Mar 7. PMID:11884384[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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