PTPRM - Structure

Structure

Transmembrane PTPs are known as receptor protein tyrosine phosphatases (RPTPs). RPTPs are single pass transmembrane proteins usually with one or two catalytic domains in their intracellular domain (the part of the protein that is inside the cell) and diverse extracellular structures (the part of the protein that is outside the cell).

PTPmu possesses an extracellular region, a single transmembrane region, a 158 amino acid long juxtamembrane domain and two tandem tyrosine phosphatase domains (referred to as D1 and D2) in its intracellular domain, and thus represents an RPTP. Only the membrane proximal phosphatase domain, D1, is catalytically active. The extracellular region contains a meprin-A5 antigen-PTP mu (MAM) domain, an Ig-like domain and four fibronectin type III-like repeats. There are other RPTPs that resemble PTPmu. These proteins are all grouped as type IIb RPTPs, and include PTPkappa (κ), PTPrho (ρ), and PCP-2. The structure of type IIb RPTPs classifies them as members of the immunoglobulin superfamily of cell adhesion molecules, in addition to being tyrosine phosphatases. The structure of PTPmu suggests that it can regulate cell adhesion and migration using its extracellular cell adhesion molecule features, while also regulating the level of tyrosine phosphorylation inside of cells using its catalytic tyrosine phosphatase domain. A series of reviews have been written about RPTPs including PTPmu. PTPmu is expressed in different organ tissues in the body, including the lung, heart and brain, pancreas, endothelial cells in capillaries and arteries throughout the body, and in retinal and brain cells. PTPmu has been shown to increase the mRNA of the K+ channel Kv1.5 in cardiac myocytes when CHO cells expressing PTPmu are cultured with cardiac myocytes.