REGULATORY MECHANISMS OF PROTEIN TYROSINE PHOSPHATASES

蛋白质酪氨酸磷酸化的稳态水平依赖于 蛋白酪氨酸磷酸酶（PTPs）的相对活性， 蛋白酪氨酸激酶。 PTP活性的调节构成了 控制细胞功能的重要机制， 蛋白质酪氨酸磷酸化，如生长和发育。 尽管最近在确定新的PTPs方面取得了进展， 关于它们的底物、调节和细胞功能。 这些拟议研究的主要目标是阐明 控制PTP生物活性的调节机制。 我们 将研究两种非受体酶的功能和调节， T细胞PTP和不同的杆状病毒PTP。 底物偏好 T细胞PTP的细胞内定位受其C- 末端域 使用体外诱变，我们将确定 C-末端结构域中特定位点的位置， 调节底物特异性。 免疫荧光将用于 确定T细胞PTP定位的精确细胞内位点。 疏水性C-末端片段的诱变将用于确定 它是否负责酶的定位。 我们已经鉴定了一种由杆状病毒Autographa编码的PTP（BVP）， 加利福尼亚州。 BVP和两个细胞同源物组成了一个新的亚家族， 内切酶 我们将研究功能，调节机制， 通过分析BVP在病毒功能中的作用，确定BVP的底物。 是 重要的是要确定是否哺乳动物形式的这个亚科存在， 如果是，以确定它们在控制酪氨酸磷酸化中的作用。 我们 有证据表明存在人类同源物，并将分离cDNA 克隆编码它，以便它可以表达和表征。 活性不受调节导致的异常酪氨酸磷酸化 致癌性酪氨酸激酶被认为是一个重要事件， 到细胞转化。 PTP调节的知识对于 了解蛋白质酪氨酸激酶和 PTPs在肿瘤发生和正常细胞生长过程中均得以维持。 获得的关于PTPs功能和调节的信息可能导致 开发用于操纵酪氨酸水平的方法 磷酸化可能在研究和治疗 疾病，如癌症。

The steady state level of protein tyrosine phosphorylation is dependent upon the relative activities of protein tyrosine phosphatases (PTPs) and protein tyrosine kinases. Regulation of PTP activity constitutes an important mechanism for controlling cellular functions which are mediated by protein tyrosine phosphorylation such as growth and development. Despite recent progress in identifying new PTPs, relatively little is known about their substrates, regulation, and cellular functions. The broad objective of these proposed studies is to elucidate the regulatory mechanisms that control the biological activities of PTPs. We will investigate the function and regulation of two nonreceptor enzymes, the T-cell PTP and a distinct baculoviral PTP. The substrate preference and intracellular localization of the T-cell PTP are regulated by its C- terminal domain. Using in vitro mutagenesis, we will determine the location of specific sites within the C-terminal domain that act to regulate substrate specificity. Immunofluorescence will be used to determine the precise intracellular site where the T-cell PTP is localized. Mutagenesis of a hydrophobic, C-terminal segment will be used to determine whether it is responsible for localization of the enzyme. We have identified a PTP (BVP)that is encoded by a baculovirus, Autographa californica. BVP and two cellular homologs comprise a new subfamily of enzymes. We will investigate the function, mechanism of regulation, and substrates of the BVP by analyzing its role in viral function. It is important to determine whether mammalian forms of this subfamily exist and if so, to define their role in controlling tyrosine phosphorylation. We have evidence for the existence of a human homolog and will isolate a cDNA clone encoding it so that it can be expressed and characterized. Aberrant tyrosine phosphorylation resulting from the unregulated activity of oncogenic tyrosine kinases is thought to be an important event leading to cellular transformation. Knowledge of PTP regulation is crucial to understanding how the delicate balance between protein tyrosine kinases and PTPs is maintained during both oncogenesis and normal cell growth. Information gained about the function and regulation of PTPs may lead to the development of methods for manipulating the level of tyrosine phosphorylation that may have application in research and treatment of diseases such as cancer.