Carboxyl-terminal PDZ ligand of neuronal nitric oxide synthase protein (CAPON) Phosphotyrosine-binding (PTB) domain
CAPON (also known as Nitric oxide synthase 1 adaptor protein, NOS1AP, encodes a cytosolic protein that binds to the signaling molecule, neuronal NOS (nNOS). It contains a N-terminal PTB domain that binds to the small monomeric G protein, Dexras1 and a C-terminal PDZ-binding domain that mediates interactions with nNOS. Included in this cd are C. elegan proteins dystrobrevin, DYB-1, which controls neurotransmitter release and muscle Ca(2+) transients by localizing BK channels and DYstrophin-like phenotype and CAPON related,DYC-1, which is functionally related to dystrophin homolog, DYS-1. Mutations in the dystrophin gene causes Duchenne muscular dystrophy. DYS-1 shares sequence similarity, including key motifs, with their mammalian counterparts. These CAPON-like proteins all have a single PTB domain. PTB domains have a common PH-like fold and are found in various eukaryotic signaling molecules. This domain was initially shown to binds peptides with a NPXY motif with differing requirements for phosphorylation of the tyrosine, although more recent studies have found that some types of PTB domains can bind to peptides lack tyrosine residues altogether. In contrast to SH2 domains, which recognize phosphotyrosine and adjacent carboxy-terminal residues, PTB-domain binding specificity is conferred by residues amino-terminal to the phosphotyrosine. PTB domains are classified into three groups: phosphotyrosine-dependent Shc-like, phosphotyrosine-dependent IRS-like, and phosphotyrosine-independent Dab-like PTB domains. This cd is part of the Dab-like subgroup.
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