Sonnenburg Erica Dutil, Bilwes Alexandrine, Hunter Tony, Noel Joseph P
Structural Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, California 92037, USA.
Biochemistry. 2003 Jul 8;42(26):7904-14. doi: 10.1021/bi0340503.
The receptor protein tyrosine phosphatase alpha (RPTPalpha) is a transmembrane receptor with two intracellular protein tyrosine phosphatase domains, a catalytically active membrane proximal domain (D1) and a membrane distal phosphatase domain with minimal catalytic activity (D2). Here we elucidate the crystal structure of RPTPalpha's D2 domain. Unlike D1, D2 exists as a monomer and lacks the N-terminal inhibitory wedge motif. The N-terminal portion of D2 is disordered, and this region linking D1 to D2 is proteolytically labile in solution whether part of D2 alone or tethered to D1, indicating that the polypeptide backbone of this part of D2 is highly flexible, and therefore accessible to proteases under native conditions. Furthermore, we have crystallized the SH2 domain of the protein tyrosine kinase c-Src, a RPTPalpha substrate, with a phosphopeptide encompassing the C-terminal phosphorylation site of D2 (pTyr789). The SH2 domain of Src binds RPTPalpha in an extended conformation. The structural and functional data support a D1-D2 arrangement with significant flexibility between phosphatase domains of RPTPalpha that is likely to be important for dynamic alterations in intra- and/or intermolecular interactions that are critical for RPTPalpha function.
受体蛋白酪氨酸磷酸酶α（RPTPα）是一种跨膜受体，具有两个细胞内蛋白酪氨酸磷酸酶结构域，一个具有催化活性的膜近端结构域（D1）和一个催化活性最小的膜远端磷酸酶结构域（D2）。在此，我们阐明了RPTPα的D2结构域的晶体结构。与D1不同，D2以单体形式存在，且缺乏N端抑制楔基序。D2的N端部分无序，并且无论单独作为D2的一部分还是与D1相连，该连接D1和D2的区域在溶液中对蛋白水解不稳定，这表明D2这部分的多肽主链具有高度灵活性，因此在天然条件下易被蛋白酶作用。此外，我们使蛋白酪氨酸激酶c-Src（一种RPTPα底物）的SH2结构域与包含D2 C端磷酸化位点（pTyr789）的磷酸肽结晶。Src的SH2结构域以伸展构象结合RPTPα。结构和功能数据支持RPTPα磷酸酶结构域之间具有显著灵活性的D1-D2排列方式，这可能对分子内和/或分子间相互作用的动态改变很重要，而这些相互作用对RPTPα的功能至关重要。
