Mickelson K E, Harding G B, Forsthoefel M, Westphal U
Biochemistry. 1982 Feb 16;21(4):654-60. doi: 10.1021/bi00533a010.
Human corticosteroid-binding globulin (CBG) forms a dimer that was isolated by gel filtration, has full binding affinity and capacity, and can be dissociated to the monomer. Monomeric CBG consists of two distinct molecular variants, which were detected by polyacrylamide gel electrophoresis in the presence and absence of sodium dodecyl sulfate. The two monomeric CBG species were separated by preparative gel electrophoresis and were found to bind cortisol, as well as progesterone, with equal affinity. They have one steroid binding site per CBG molecule. Amino acid and carbohydrate analyses are essentially the same for both of the CBG variants. Removal of sialic acid or 90% of the carbohydrate did not affect the existence of the two molecular forms. The two CBG species were isolated from each of the sera from five individual donors, indicating that the observed heterogeneity does not result from pooling genetic variants. The two species are immunologically identical. A possible explanation for the existence of the two electrophoretic variants is a difference in amidation.
人皮质类固醇结合球蛋白（CBG）形成一种二聚体，通过凝胶过滤分离得到，具有完全的结合亲和力和容量，并且可以解离为单体。单体CBG由两种不同的分子变体组成，这两种变体在有和没有十二烷基硫酸钠存在的情况下通过聚丙烯酰胺凝胶电泳检测到。通过制备性凝胶电泳分离出这两种单体CBG物种，发现它们以相同的亲和力结合皮质醇以及孕酮。每个CBG分子有一个类固醇结合位点。两种CBG变体的氨基酸和碳水化合物分析基本相同。去除唾液酸或90%的碳水化合物并不影响这两种分子形式的存在。从五个个体供体的每份血清中都分离出了这两种CBG物种，这表明观察到的异质性并非来自混合遗传变体。这两种物种在免疫上是相同的。这两种电泳变体存在的一个可能解释是酰胺化的差异。
