Miwa T, Nonaka M, Okada N, Wakana S, Shiroishi T, Okada H
Department of Molecular Biology, Nagoya City University School of Medicine, Nagoya, 467-8601, Japan.
Immunogenetics. 1998 Nov-Dec;48(6):363-71. doi: 10.1007/s002510050447.
Human membrane cofactor protein (MCP, CD46) is widely distributed and is one of the plasma membrane complement inhibitors. We isolated cDNA clones encoding genetic homologues of human MCP from a rat testis cDNA library. Northern blot analysis indicated that rat MCP is preferentially expressed in testis, similar to what is found with guinea pig MCP. We identified several different cDNAs, which were presumably generated by alternative splicing from a single-copy gene. The most prevalent isoform corresponded to the Ser/Thr/Pro-rich C type of human MCP. Mouse MCP cDNA was cloned by polymerase chain reaction based on the nucleotide sequence of rat MCP. The deduced amino acid sequence showed 77.8% identity to rat MCP. Mouse MCP was also preferentially expressed in testis. Unique expression in testis in rat and mouse as well as guinea pig suggests that MCPs in these species not only act as complement regulatory proteins but may also have more specialized functions in fertilization or reproduction. Genetic mapping by linkage analysis indicated that the mouse Mcp gene is located on distal chromosome 1, closely linked to the complement receptor 2 (Cr2) gene.
人膜辅因子蛋白（MCP，CD46）分布广泛，是一种质膜补体抑制剂。我们从大鼠睾丸cDNA文库中分离出编码人MCP基因同源物的cDNA克隆。Northern印迹分析表明，大鼠MCP在睾丸中优先表达，这与豚鼠MCP的情况相似。我们鉴定出了几种不同的cDNA，推测它们是由单拷贝基因的可变剪接产生的。最普遍的异构体对应于人MCP富含丝氨酸/苏氨酸/脯氨酸的C型。基于大鼠MCP的核苷酸序列，通过聚合酶链反应克隆了小鼠MCP cDNA。推导的氨基酸序列与大鼠MCP的同一性为77.8%。小鼠MCP也在睾丸中优先表达。大鼠、小鼠以及豚鼠在睾丸中的独特表达表明，这些物种中的MCP不仅作为补体调节蛋白发挥作用，而且在受精或生殖过程中可能还具有更特殊的功能。通过连锁分析进行的基因定位表明，小鼠Mcp基因位于1号染色体远端，与补体受体2（Cr2）基因紧密连锁。
