Description | Proteins encoding phosphotyrosine binding (PTB) domains function as adaptors or scaffolds to organise the signaling complexes involved in wide-ranging physiological processes including neural development, immunity, tissue homeostasis and cell growth. Due to structural differences, PTB domains are divided into three groups represented by phosphotyrosine-dependent IRS-like, phosphotyrosine-dependent Shc-like, and phosphotyrosine-independent Dab-like PTBs. The last two PTBs have been named as phosphotyrosine interaction domain (PID or PI domain). PID domain has an average length of about 160 amino acids [ ].The Shc-like PID specifically binds to the Asn-Pro-Xaa-Tyr(P) motif found in many tyrosine-phosphorylated proteins including growth factor receptors. On the other hand the Dab-like PID domain binds to non-phosphorylated tyrosine residue or even a phenylalanine at the same position [ ]. Most of the ligands for Shc-like PID domains are RTK or cytokine, whereas phosphotyrosine independent Dab-like PID domains seems to mediate other types of signaling pathways, like endocytosis/processing or exocytosis. This domain binds both peptides and headgroups of phosphatidylinositides, utilising two distinct binding motifs to mediate spatial organisation and localisation within cells [ , , , ].The 3D structure of PID domain has been solved [ ]. It shares a folding pattern, commonly referred to as the PH-domain "superfold". The core "superfold"consists of seven antiparallel β strands forming two orthogonal β sheets. This β sandwich is capped at the C terminus by an α helix. It contains a peptide binding pocket (formed by the β strand 5 and C-terminal α helix) and a highly basic phospholipid binding "crown"(largely composed of residues from loop regions near the N terminus). Both Shc and Dab1 have two additional α helices, one of which is located at the N terminus and the other between β1 and β2 strands. | Name | PTB/PI domain |
Short Name | PTB/PI_dom | Type | Domain |