Ballard L, Seya T, Teckman J, Lublin D M, Atkinson J P
J Immunol. 1987 Jun 1;138(11):3850-5.
Membrane cofactor protein (MCP or gp45-70) is a recently described regulatory glycoprotein of the complement system which binds iC3 or C3b and is present on human platelets, T cells, B cells, monocytes, and mononuclear-derived cell lines. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, MCP migrates as a doublet with an Mr of the upper band of 63,000 and the lower band of 58,000. The same pattern was found on all cell populations in a given individual and was stable over time. In order to further characterize the two band pattern on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, MCP was isolated by affinity chromatography or immunoprecipitation from 72 healthy unrelated donors. All individuals expressed both bands and, based on the densitometric scanning of gels, three patterns were noted: upper band predominant in 65%, approximately equal distribution of upper and lower bands in 29%, and lower band predominant in 6%. These observed phenotypic frequencies fit with expectations based on Hardy-Weinberg equilibrium for a two-allele system. Family studies also support this model as none of the 26 offspring had a phenotype that deviated from the expected, assuming an autosomal codominant model of inheritance. These results are consistent with a simple two-allele system that controls the expression of the two bands of MCP.
膜辅助蛋白（MCP或gp45 - 70）是补体系统中一种最近被描述的调节性糖蛋白，它能结合iC3或C3b，存在于人类血小板、T细胞、B细胞、单核细胞以及单核细胞衍生的细胞系上。在十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳中，MCP以双峰形式迁移，上带的Mr为63,000，下带的Mr为58,000。在给定个体的所有细胞群体中都发现了相同的模式，并且随时间稳定。为了进一步表征十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳上的两条带模式，通过亲和层析或免疫沉淀从72名健康无关供体中分离出MCP。所有个体都表达两条带，基于凝胶的光密度扫描，观察到三种模式：65%的个体上带为主，29%的个体上下带分布大致相等，6%的个体下带为主。这些观察到的表型频率符合基于双等位基因系统的哈迪 - 温伯格平衡的预期。家系研究也支持该模型，因为假设为常染色体共显性遗传模型，26名后代中没有一个的表型偏离预期。这些结果与控制MCP两条带表达的简单双等位基因系统一致。
