catalytic domain of type IIb (or R2B) subfamily receptor-type tyrosine-protein phosphatases, repeat 1
The type II (or R2B) subfamily of receptor protein tyrosine phosphatases (RPTPs) include the prototypical member PTPmu (or PTPRM), PCP-2 (or PTPRU), PTPrho (or PTPRT), and PTPkappa (or PTPRK). They belong to the larger family of classical tyrosine-specific protein tyrosine phosphatases (PTPs). PTPs (EC 3.1.3.48) catalyze the dephosphorylation of phosphotyrosine peptides. Type IIb RPTPs mediate cell-cell adhesion though homophilic interactions; their ligand is an identical molecule on an adjacent cell. No heterophilic interactions between the subfamily members have been observed. They also commonly function as tumor suppressors. They contain an extracellular region with an Meprin-A5 (neuropilin)-mu (MAM) domain, an immunoglobulin (Ig) domain, and four fibronectin type III (FN3) repeats, a transmembrane domain, and an intracellular segment with a juxtamembrane domain similar to the cytoplasmic domain of classical cadherins and two tandem PTP domains. This model represents the first (repeat 1) PTP domain.
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