Gum J R, Hicks J W, Lagace R E, Byrd J C, Toribara N W, Siddiki B, Fearney F J, Lamport D T, Kim Y S
Gastrointestinal Research Laboratory, Department of Veterans Affairs Medical Center, San Francisco, California 94121.
J Biol Chem. 1991 Nov 25;266(33):22733-8.
We have prepared antisera to deglycosylated rat intestinal mucin and used it to obtain immunoreactive clones from a rat jejunum cDNA library. Four of these clones were sequenced, and all were found to be partial cDNAs that contained 18-base pair tandem repeats characteristic of a mucin. These cDNAs encoded a repetitive peptide with a consensus sequence of TTTPDV. Thus, they bear little resemblance to either of the two human intestinal mucin cDNAs isolated previously (Gum, J. R., Byrd, J. C., Hicks, J. W., Toribara, N. W., Lamport, D. T. A., and Kim, Y. S. (1989) J. Biol. Chem. 264, 6480-6487 and Gum, J. R., Hicks, J. W., Swallow, D. M., Lagace, R. E., Byrd, J. C., Lamport, D. T. A., Siddiki, B., and Kim, Y. S. (1990) Biochem. Biophys. Res. Commun. 171, 407-415). One of these rat mucin clones, designated RMUC 176, was chosen for further analysis. This clone recognized a band of approximately 9 kilobases when used to probe RNA blots. A strong hybridization band was present using rat small intestine and colon RNA but was not detectable when RNA isolated from heart, liver, or kidney was tested. The RMUC 176 clone and the two previously isolated human intestinal mucin cDNA clones were used to probe blots prepared from BamHI-digested DNA of various species. Here, the human probes detected fragments present only in human and chimpanzee DNA, whereas the RMUC 176 clone recognized fragments only in rat and mouse DNA. Thus, the repetitive portions of intestinal mucin genes are apparently not well conserved between phylogenetically distant species.
我们制备了针对去糖基化大鼠肠粘蛋白的抗血清，并利用它从大鼠空肠cDNA文库中获得免疫反应性克隆。对其中4个克隆进行了测序，发现它们均为部分cDNA，含有粘蛋白特有的18个碱基对的串联重复序列。这些cDNA编码一个共有序列为TTTPDV的重复肽段。因此，它们与先前分离的两个人类肠粘蛋白cDNA几乎没有相似之处（Gum, J. R., Byrd, J. C., Hicks, J. W., Toribara, N. W., Lamport, D. T. A., and Kim, Y. S. (1989) J. Biol. Chem. 264, 6480 - 6487以及Gum, J. R., Hicks, J. W., Swallow, D. M., Lagace, R. E., Byrd, J. C., Lamport, D. T. A., Siddiki, B., and Kim, Y. S. (1990) Biochem. Biophys. Res. Commun. 171, 407 - 415）。选择其中一个大鼠粘蛋白克隆，命名为RMUC 176，进行进一步分析。当用该克隆探测RNA印迹时，识别出一条约9千碱基的条带。使用大鼠小肠和结肠RNA时出现强杂交带，但检测从心脏、肝脏或肾脏分离的RNA时未检测到。RMUC 176克隆以及先前分离的两个人类肠粘蛋白cDNA克隆用于探测由各种物种的BamHI消化DNA制备的印迹。在此，人类探针检测到仅存在于人类和黑猩猩DNA中的片段，而RMUC 176克隆仅识别大鼠和小鼠DNA中的片段。因此，肠粘蛋白基因的重复部分在系统发育上距离较远的物种之间显然没有得到很好的保守。
