Bovine submaxillary mucin contains multiple domains and tandemly repeated non-identical sequences
Bovine submaxillary mucin contains multiple domains and tandemly repeated non-identical sequences
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DOI：
10.1042/bj3310193
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发表时间：
1998-04-01
影响因子：
4.1
通讯作者：
Bhavanandan, VP
中科院分区：
文献类型：
--
作者：
Jiang, WP;Woitach, JT;Bhavanandan, VP
克隆了牛颌下粘蛋白（BSM）的一系列cDNA片段，并测定了最大克隆BSM 421的核苷酸序列。从纯化的apoBSM中确定的两个肽序列被发现在BSM 421的粘蛋白编码区的N-末端附近。该克隆不含起始或终止密码子，但其3'末端与先前分离的克隆λ BSM 10的5'末端重叠。1589个氨基酸残基的复合序列由五个不同的蛋白质结构域组成，从C-末端开始编号。富含半胱氨酸的结构域I可以进一步分为血管性血友病因子C型重复序列和胱氨酸结。结构域III和V由具有平均47个残基的相似重复肽序列组成。结构域II和IV不包含这样的序列，但与结构域III和V相似，富含丝氨酸和苏氨酸，其中许多被预测为潜在的O-糖基化位点。结构域III还包含两个与ATP/GTP结合位点基序A（P环）匹配的序列。对于部分推导的氨基酸序列，预测只有β-链而没有α-螺旋。用BSM 421探针对颌下腺RNA进行北方分析，发现了1.1 ~ 10 kb以上的BSM多条信息。串联重复的，不相同的肽序列的约。BSM的结构域III和V中的47个残基与猪颌下粘蛋白（PSM）的串联重复的相同的81个残基序列不同，尽管BSM和PSM都含有相似的C-末端结构域。相反，绵羊颌下粘蛋白的两个肽序列与BSM结构域V中的相应序列高度相似（分别为86%和65%相同）。
A number of cDNA fragments coding for bovine submaxillary mucin (BSM) were cloned, and the nucleotide sequence of the largest clone, BSM421, was determined. Two peptide sequences determined from the purified apoBSM were found near the N-terminus of the mucin-coding region of BSM421. This clone does not contain a start or stop codon, but its 3' end overlaps with the 5' end of a previously isolated clone, lambda BSM10. The composite sequence of 1589 amino acid residues consists of five distinct protein domains, which are numbered from the C-terminus. The cysteine-rich domain I can be further divided into a von Willebrand factor type C repeat and a cystine knot. Domains III and V consist of similar repeated peptide sequences with an average of 47 residues. Domains II and IV do not contain such sequences but are similar to domains III and V in being rich in serine and threonine, many of which are predicted to be potential O-glycosylation sites. Domain III also contains two sequences that match the ATP/GTP-binding site motif A (P-loop). Only beta-strands and no alpha-helices are predicted for the partial deduced amino acid sequence. Northern analysis of submaxillary gland RNA with the BSM421 probe detected multiple messages of BSM with sizes from 1.1 to over 10 kb. The tandemly repeated, non-identical peptide sequences of approx. 47 residues in domains III and V of BSM differ from the tandemly repeated, identical 81-residue sequences of pig submaxillary mucin (PSM), although both BSM and PSM contain similar C-terminal domains. In contrast, two peptide sequences of ovine submaxillary mucin are highly similar (86% and 65% identical respectively) to the corresponding sequences in domain V of BSM.