Fruman D A, Cantley L C, Carpenter C L
Division of Signal Transduction, Beth Israel Hospital, Boston, Massachusetts, USA.
Genomics. 1996 Oct 1;37(1):113-21. doi: 10.1006/geno.1996.0527.
Phosphoinositide 3-kinase is a lipid and protein kinase composed of a 110-kDa catalytic subunit and an 85-kDa (p85) or 55-kDa (p55) regulatory subunit. In mammals, at least two genes encode catalytic subunits, and at least three genes encode regulatory subunits. Here we report the cloning and structural analysis of the mouse p85 alpha gene. The translated portion of mouse p85 alpha is encoded by 15 exons that span at least 40 kb. We have cloned an alternatively spliced form of p85 alpha from both mouse and rat cDNA libraries. This splice variant encodes a unique 5'-untranslated region, start codon, and 6-amino-acid aminoterminus followed by the carboxyterminal 418 amino acids of p85 alpha. A corresponding exon is present within the p85 alpha genomic locus. In vitro transcription and translation of the splice variant cDNA generate a protein of approximately 45 kDa that is reactive with an anti-p85 alpha antiserum. Northern blot analysis of mouse tissues reveals differential expression of full-length and alternatively spliced p85 alpha, with the splice variant most abundant in the liver.
磷脂酰肌醇3激酶是一种脂质和蛋白激酶，由一个110 kDa的催化亚基和一个85 kDa（p85）或55 kDa（p55）的调节亚基组成。在哺乳动物中，至少有两个基因编码催化亚基，至少有三个基因编码调节亚基。在此我们报道小鼠p85α基因的克隆及结构分析。小鼠p85α的编码区由15个外显子组成，跨越至少40 kb。我们从小鼠和大鼠的cDNA文库中克隆出了p85α的一种可变剪接形式。这种剪接变体编码一个独特的5'-非翻译区、起始密码子和6个氨基酸的氨基末端，随后是p85α的羧基末端418个氨基酸。在p85α基因座内存在一个相应的外显子。对剪接变体cDNA进行体外转录和翻译可产生一种约45 kDa的蛋白质，它能与抗p85α抗血清发生反应。对小鼠组织进行Northern印迹分析显示，全长和可变剪接的p85α存在差异表达，剪接变体在肝脏中最为丰富。
