大鼠变异型甲胎蛋白的特性分析

Characterization of a rat variant alpha-fetoprotein.

作者信息

Watanabe T, Jimenez-Molina J L, Chou J Y

机构信息

Human Genetics Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.

出版信息

Biochem Biophys Res Commun. 1992 Jun 15;185(2):648-56. doi: 10.1016/0006-291x(92)91674-f.

DOI:10.1016/0006-291x(92)91674-f

PMID:1376990

Abstract

The rat adult liver and hepatocyte lines express an 1.7-kb variant alpha-fetoprotein (AFP) mRNA which differs from the 2.2-kb fetal AFP transcript in sequence in the 5' region. Here we report the characterization of a variant AFP cDNA, ARFP9, which is 1349 bp in length and encodes a 325 amino acid polypeptide. Nucleotides 225 to the 3' end (1125 bp) in ARFP9 corresponds exactly to nucleotide 873 to the 3' end of the fetal AFP mRNA. However, the first 224-bp of ARFP9, which is located in the 7th intron (designated the V exon) of the rat AFP gene, is not present in the 2.2-kb fetal AFP transcript. The size of the V exon is about 266-bp. In vitro expression experiments showed that the variant AFP is an unglycosylated intracellular protein of 37 kDa. Methyl-isobutyl-xanthine (MIX) stimulated expression of the fetal AFP mRNA but inhibited expression of the variant AFP mRNA, suggesting that in the rat, the two AFP transcripts are developmentally and differentially regulated.

摘要

成年大鼠肝脏和肝细胞系表达一种1.7 kb的甲胎蛋白（AFP）变异体mRNA，其在5'区域的序列与2.2 kb的胎儿AFP转录本不同。在此，我们报道了一种变异体AFP cDNA，即ARFP9的特征，其长度为1349 bp，编码一个325个氨基酸的多肽。ARFP9中从核苷酸225到3'端（1125 bp）与胎儿AFP mRNA从核苷酸873到3'端完全对应。然而，ARFP9的前224 bp位于大鼠AFP基因的第7内含子（命名为V外显子）中，并不存在于2.2 kb的胎儿AFP转录本中。V外显子的大小约为266 bp。体外表达实验表明，变异体AFP是一种37 kDa的未糖基化细胞内蛋白。甲基异丁基黄嘌呤（MIX）刺激胎儿AFP mRNA的表达，但抑制变异体AFP mRNA的表达，这表明在大鼠中，两种AFP转录本在发育过程中受到不同的调控。