Sap J, Jiang Y P, Friedlander D, Grumet M, Schlessinger J
Department of Pharmacology, New York University Medical Center, New York 10016.
Mol Cell Biol. 1994 Jan;14(1):1-9. doi: 10.1128/mcb.14.1.1-9.1994.
Receptor tyrosine phosphatases (R-PTPases) feature PTPase domains in the context of a receptor-like transmembrane topology. The R-PTPase R-PTP-kappa displays an extracellular domain composed of fibronectin type III motifs, a single immunoglobulin domain, as well as a recently defined MAM domain (Y.-P. Jiang, H. Wang, P. D'Eustachio, J.M. Musacchio, J. Schlessinger, and J. Sap, Mol. Cell. Biol. 13:2942-2951, 1993). We report here that R-PTP-kappa can mediate homophilic intercellular interaction. Inducible expression of the R-PTP-kappa protein in heterologous cells results in formation of stable cellular aggregates strictly consisting of R-PTP-kappa-expressing cells. Moreover, the purified extracellular domain of R-PTP-kappa functions as a substrate for adhesion by cells expressing R-PTP-kappa and induces aggregation of coated synthetic beads. R-PTP-kappa-mediated intercellular adhesion does not require PTPase activity or posttranslational proteolytic cleavage of the R-PTP-kappa protein and is calcium independent. The results suggest that R-PTPases may provide a link between cell-cell contact and cellular signaling events involving tyrosine phosphorylation.
受体酪氨酸磷酸酶（R - PTPases）在受体样跨膜拓扑结构中具有PTPase结构域。R - PTPase R - PTP - κ具有一个由III型纤连蛋白基序组成的胞外结构域、一个单一的免疫球蛋白结构域以及一个最近定义的MAM结构域（Y.-P. Jiang、H. Wang、P. D'Eustachio、J.M. Musacchio、J. Schlessinger和J. Sap，《分子与细胞生物学》13:2942 - 2951，1993年）。我们在此报告，R - PTP - κ可介导同种型细胞间相互作用。R - PTP - κ蛋白在异源细胞中的诱导表达导致形成稳定的细胞聚集体，该聚集体严格由表达R - PTP - κ的细胞组成。此外，纯化的R - PTP - κ胞外结构域可作为表达R - PTP - κ的细胞的黏附底物，并诱导包被的合成珠聚集。R - PTP - κ介导的细胞间黏附不需要PTPase活性或R - PTP - κ蛋白的翻译后蛋白水解切割，且不依赖于钙。结果表明，R - PTPases可能在细胞 - 细胞接触与涉及酪氨酸磷酸化的细胞信号事件之间提供联系。
