The protein Hck is a member of the Src family of non-receptor tyrosine kinases which is preferentially expressed in haematopoietic cells of the myeloid and B-lymphoid lineages. Src kinases are inhibited by tyrosine-phosphorylation at a carboxy-terminal site. The SH2 domains of these enzymes play an essential role in this regulation by binding to the tyrosine-phosphorylated tail. The SH2 domain of Hck regulates enzymatic activity indirectly; intramolecular interactions between the SH3 and catalytic domains appear to stabilize an inactive form of the kinase. The HIV-1 Nef protein, which is a high-affinity ligand for the Hck SH3 domain, binds to either the downregulated or activated form of Hck causing a large increase in Hck catalytic activity. The intact SH3-binding motif in Nef is crucial for Hck activation.
Stahl, SJ, Wingfield, PT, Grzesiek, S, Clore, GM, Bax, A, Hu, JS, Palmer, I, Gronenborn, AM, Kaufman, J
Baltimore, D, Cheng, G, Saksela, K
Sicheri, F, LaFevre-Bernt, M, Miller, WT, Moarefi, I, Huse, M, Kuriyan, J, Lee, CH
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