Meseguer M, Pellicer A, Simón C
Department of Pediatrics, Obstetrics and Gynecology, Valencia University School of Medicine and Instituto Valenciano de Infertilidad Valencia, Spain.
Mol Hum Reprod. 1998 Dec;4(12):1089-98. doi: 10.1093/molehr/4.12.1089.
Mucins, best known as the major constituent of mucus, are a family of highly glycosylated, high molecular weight (> or = 200 kDa) glycoproteins present on the surface of human epithelial cells. MUC1 has the features of an integral membrane protein. It has an extracellular tandem repeat domain that forms the major part of the core protein, and results in a highly repetitive structure, which is extremely immunogenic. In the protein there is also a proteolytic cleavage site reported in the proximal extracellular domain. The secreted form of MUC1 lacks the cytoplasmic tail, but it is not clear whether this results from alternative splicing or proteolysis and release of the free extracellular domain. The locus of the MUC1 gene is on band 21 of the long arm of chromosome 1 (1q21). Anti-adhesion properties of this mucin are probably the result of the unique structure of the molecule. In mouse uterine epithelium, the homologue MUC1 is regulated with reduced expression in the implantation period, but in humans, expression is high during the peri-implantation period. MUC1 may inhibit the interaction between trophoblast and apical epithelium adhesion molecules at the time of implantation, giving the possibility of forming a uterine barrier for implantation.
黏蛋白作为黏液的主要成分而广为人知，是一类高度糖基化的高分子量（≥200 kDa）糖蛋白，存在于人类上皮细胞表面。MUC1具有整合膜蛋白的特征。它有一个细胞外串联重复结构域，构成核心蛋白的主要部分，并导致高度重复的结构，这种结构具有极强的免疫原性。在该蛋白的近端细胞外结构域还报道存在一个蛋白水解切割位点。MUC1的分泌形式缺乏细胞质尾，但尚不清楚这是由于可变剪接还是蛋白水解以及游离细胞外结构域的释放所致。MUC1基因定位于1号染色体长臂的21带（1q21）。这种黏蛋白的抗黏附特性可能是该分子独特结构的结果。在小鼠子宫上皮中，同源物MUC1在植入期表达下调，但在人类中，植入前期表达较高。MUC1可能在植入时抑制滋养层与顶端上皮黏附分子之间的相互作用，从而有可能形成子宫植入屏障。
