Vojtek A B, Cooper J A
Fred Hutchinson Cancer Research Center, Seattle, WA 98104.
J Cell Sci. 1993 Jul;105 ( Pt 3):777-85. doi: 10.1242/jcs.105.3.777.
CAP, an adenylyl cyclase associated protein, is present in Saccharomyces cerevisiae and Schizosaccharomyces pombe. In both organisms, CAP is bifunctional: the N-terminal domain binds to adenylyl cyclase, thereby enabling adenylyl cyclase to respond appropriately to upstream regulatory signals, such as RAS in S. cerevisiae; the C-terminal domain is required for cellular morphogenesis. Here, we describe the isolation of a cDNA encoding a CAP homolog from a higher eukaryote. The mouse CAP cDNA contains an open reading frame capable of encoding a 474 amino acid protein. The protein encoded by the mouse CAP cDNA shows extensive homology to the yeast CAP proteins, particularly in the central poly-proline rich region and in the C-terminal domain. By northern analysis, the CAP message appears to be ubiquitous, but not uniform. By indirect immunofluorescence, ectopically expressed mouse CAP protein is found in the cytoplasm of fibroblasts and, in migrating cells, at the leading edge. Expression of the mouse CAP cDNA in S. cerevisiae complements defects associated with loss of the yeast CAP carboxy-terminal domain. Hence, the function of the CAP carboxy-terminal domain has been conserved from yeast to mouse.
CAP是一种与腺苷酸环化酶相关的蛋白质，存在于酿酒酵母和粟酒裂殖酵母中。在这两种生物体中，CAP具有双重功能：N端结构域与腺苷酸环化酶结合，从而使腺苷酸环化酶能够对上游调节信号做出适当反应，例如酿酒酵母中的RAS；C端结构域是细胞形态发生所必需的。在此，我们描述了从一种高等真核生物中分离出编码CAP同源物的cDNA。小鼠CAP cDNA包含一个能够编码474个氨基酸蛋白质的开放阅读框。小鼠CAP cDNA编码的蛋白质与酵母CAP蛋白质具有广泛的同源性，特别是在富含多聚脯氨酸的中央区域和C端结构域。通过Northern分析，CAP信息似乎普遍存在，但并不均匀。通过间接免疫荧光法，在成纤维细胞的细胞质中以及迁移细胞的前沿发现了异位表达的小鼠CAP蛋白。小鼠CAP cDNA在酿酒酵母中的表达弥补了与酵母CAP羧基末端结构域缺失相关的缺陷。因此，CAP羧基末端结构域的功能从酵母到小鼠都得到了保守。
