Molecular cloning of guinea pig membrane cofactor protein: preferential expression in testis.
Molecular cloning of guinea pig membrane cofactor protein: preferential expression in testis.
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豚鼠膜辅因子蛋白的分子克隆：在睾丸中优先表达。
DOI：
10.4049/jimmunol.157.11.4946
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发表时间：
1996
影响因子：
4.4
通讯作者：
H. Okada
中科院分区：
文献类型：
--
作者：
M. Hosokawa;M. Nonaka;N. Okada;H. Okada
人膜辅助因子蛋白（MCP）是一种广泛分布于细胞相关的补体调节蛋白，最近的研究表明MCP可能参与精子-卵子相互作用。我们从豚鼠睾丸中分离到4个cDNA克隆和1个与人MCP同源的逆转录pcr产物。这些克隆定义了五个同种异构体类，这些同种异构体类是由单个拷贝基因通过选择性剪接产生的。逆转录pcr结果显示，GMP1和GM2两类克隆占主导地位。GMP1由四个短一致重复序列（SCRs）组成，对应于人类富含丝氨酸/苏氨酸/脯氨酸的C （STP(C)）结构域和一个未知意义的人类区域，一个被认为是跨膜结构域的疏水区域和一个细胞质区域。与人MCP在SCR区的同源性在氨基酸水平为56%，在核苷酸水平为71%。GM2与GMP1具有相同的结构，不同之处是它缺少第四SCR，这被认为是人MCP的C3b结合所必需的。各种组织的Northern印迹分析显示，睾丸中MCP转录物水平显著。豚鼠MCP可能只有一个与人类STP(C)同源的STP结构域，并且在这方面与人类精子MCP相似。基因分析显示，在与人类STP(a)和STP(B)对应的豚鼠区域，存在单碱基缺失和缺乏一致的剪接序列。这些结果表明，与人类MCP相比，豚鼠MCP在生殖中发挥的作用更有限。
Human membrane cofactor protein (MCP) is a widely distributed cell-associated complement-regulatory protein, and recent findings suggest that MCP may be involved in sperm-egg interaction. We have isolated four cDNA clones and one reverse transcriptase-PCR product homologous to human MCP from guinea pig testis. These clones defined five isoform classes generated from a single copy gene by alternative splicing. Reverse transcriptase-PCR revealed that two classes for the clones termed GMP1 and GM2 were predominant. GMP1 consisted of four short consensus repeats (SCRs), regions corresponding to the human serine/threonine/proline-rich C (STP(C)) domain and a human region of unknown significance, a hydrophobic region presumed to be a transmembrane domain, and a cytoplasmic region. Identity with human MCP in the SCR region was 56% at the amino acid level and 71% at the nucleotide level. GM2 had the same structure as GMP1, except that it lacked the fourth SCR, which is presumed to be essential for C3b binding of human MCP. Northern blotting analysis of various tissues revealed a significant level of MCP transcripts in testis. Guinea pig MCP is likely to have only one STP domain that is homologous to human STP(C) and is similar in this respect to human spermatozoa MCP. Gene analysis revealed a single base deletion and a lack of consensus sequences for splicing in the guinea pig regions corresponding to human STP(A) and STP(B), respectively. These results suggest that guinea pig MCP plays a more restricted role in reproduction than does human MCP.