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)和蛋白酪氨酸磷酸酶(PTPs)的相对活性 蛋白酪氨酸激酶。对PTP活动的调节构成了一种 控制细胞功能的重要机制 受蛋白质酪氨酸磷酸化等影响生长发育。 尽管最近在确定新的PTP方面取得了进展，但人们对此知之甚少 关于它们的底物、调节和细胞功能。 这些拟议研究的广泛目标是阐明 控制PTP生物活性的调控机制。我们 将研究两种非受体酶的功能和调节， T细胞PTP和独特的杆状病毒PTP。底物偏好 而T细胞PTP的细胞内定位受其C- 终端域。利用体外诱变，我们将确定 C-末端结构域内作用于 调节底物专一性。免疫荧光将用于 确定T细胞PTP定位的准确细胞内位置。 将使用疏水C末端片段的突变来确定 它是否负责酶的定位。 我们已经鉴定出一种由杆状病毒Autograph a编码的PTP(BVP) 卡里福尼卡。BVP和两个细胞同源物组成了一个新的亚家族 酵素。我们将研究调控的功能、机制和 通过分析BVP在病毒功能中的作用，获得BVP的底物。它是 对于确定这个亚家族的哺乳动物形式是否存在以及 如果是这样的话，确定它们在控制酪氨酸磷酸化中的作用。我们 有证据证明人类同源物的存在，并将分离出一个cdna 克隆对其进行编码，以便其能够表达和表征。 非调控活性引起的酪氨酸磷酸化异常 致癌酪氨酸激酶的研究被认为是导致 到细胞转化。对PTP法规的了解对于 了解蛋白酪氨酸激酶和蛋白酪氨酸激酶之间的微妙平衡 PTPs在肿瘤发生和正常细胞生长过程中均有表达。 获得的关于PTP的功能和调节的信息可能导致 酪氨酸水平调控方法的研究进展 磷酸化可能在骨肉瘤研究和治疗中的应用 癌症等疾病。

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.