Pratt W S, Crawley S, Hicks J, Ho J, Nash M, Kim Y S, Gum J R, Swallow D M
MRC Human Biochemical Genetics Unit, University College London, 4 Stephenson Way, London, NW1 2HE, United Kingdom.
Biochem Biophys Res Commun. 2000 Sep 7;275(3):916-23. doi: 10.1006/bbrc.2000.3406.
The MUC3 gene encodes a transmembrane mucin-type glycoprotein. A number of consistent single nucleotide changes were observed in different MUC3 cDNAs from a single individual, suggesting the presence of at least three different transcripts per individual. This transcript heterogeneity is due both to the existence of a second copy of the MUC3 gene and to allelic changes. Sequencing of the second MUC3 shows that it has the same C-terminal domain and intron/exon structure as the previously described MUC3. The tandem repeat domain has the same amino acid consensus sequence but shows more substitutions. The unique exonic sequences range from 94 to 100% identity at the nucleotide level and correspondingly few amino acid changes have been identified. The introns show around 95% identity. We propose to name this second gene MUC3B, MUC3A being reserved for the first MUC3 gene. MUC3B, like MUC3A, is expressed in intestine and Caco-2 cells.
MUC3基因编码一种跨膜粘蛋白型糖蛋白。在来自同一个体的不同MUC3 cDNA中观察到一些一致的单核苷酸变化，这表明每个个体至少存在三种不同的转录本。这种转录本的异质性既归因于MUC3基因的第二个拷贝的存在，也归因于等位基因变化。对第二个MUC3的测序表明，它具有与先前描述的MUC3相同的C末端结构域和内含子/外显子结构。串联重复结构域具有相同的氨基酸共有序列，但显示出更多的替换。独特的外显子序列在核苷酸水平上的同一性为94%至100%，相应地，已鉴定出的氨基酸变化很少。内含子显示出约95%的同一性。我们建议将这个第二个基因命名为MUC3B，MUC3A则保留给第一个MUC3基因。MUC3B与MUC3A一样，在肠道和Caco-2细胞中表达。
