Dab is a cystosolic adaptor protein, which binds to the cytoplasmic tails of lipoprotein receptors, such as ApoER2 and VLDLR, via its PTB domain. The dab PTB domain has a preference for unphosphorylated tyrosine within an NPxY motif. Additionally, the Dab PTB domain, which is structurally similar to PH domains, binds to phosphatidlyinositol phosphate 4,5 bisphosphate in a manner characteristic of phosphoinositide binding PH domains. 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.
Jiyao W et al.(2023). "The conserved domain database in 2023.",