Marchetto G S, Henry H L
Department of Biochemistry, University of California, Riverside 92521, USA.
Gene. 1995 Jun 9;158(2):303-4. doi: 10.1016/0378-1119(95)00118-p.
The endogenous inhibitor of cAMP-dependent protein kinase (PKA) is down-regulated in the kidneys from vitamin-D-replete chicks as compared to vitamin-D-deficient chicks. Screening of a vitamin-D-deficient chick kidney library resulted in the isolation of a 450-bp cDNA clone encoding the 76-amino acid (aa) protein kinase inhibitor (PKI). The deduced aa sequence of avian PKI shares 80 and 41% identity with the mammalian PKI alpha and PKI beta 1 isoforms, respectively. The chick and mammalian PKI contain conserved N-terminal sequences, including the pseudo-substrate site (18GRRNA22), which are required for potent inhibition of the catalytic subunit of PKA. Chick kidney PKI contains ten unique aa in the C-terminal portion of the protein that are not shared with the mammalian PKI alpha or beta isoforms.
与维生素D缺乏的雏鸡相比，维生素D充足的雏鸡肾脏中，环磷酸腺苷（cAMP）依赖性蛋白激酶（PKA）的内源性抑制剂表达下调。对维生素D缺乏的雏鸡肾脏文库进行筛选，得到了一个450碱基对（bp）的cDNA克隆，该克隆编码76个氨基酸（aa）的蛋白激酶抑制剂（PKI）。推导的禽类PKI氨基酸序列与哺乳动物PKIα和PKIβ1亚型分别具有80%和41%的同一性。雏鸡和哺乳动物的PKI含有保守的N端序列，包括伪底物位点（18GRRNA22），这是有效抑制PKA催化亚基所必需的。雏鸡肾脏PKI在蛋白质的C端部分含有10个独特的氨基酸，这些氨基酸在哺乳动物PKIα或β亚型中不存在。
