Braesch-Andersen S, Paulie S, Koho H, Nika H, Aspenström P, Perlmann P
Department of Immunology, University of Stockholm, Sweden.
J Immunol. 1989 Jan 15;142(2):562-7.
The Ag CDw40 (p50, Bp50) is a phosphoprotein expressed on the surface of both B lymphocytes and on certain malignant cell types of nonhemopoietic origin. Antibodies to this Ag have been shown to act as a potent co-mitogen for B cells. In order to elucidate the function of this Ag, we have now investigated some of its biochemical characteristics as well as the relationship of B cell derived CDw40 to that derived from urinary bladder carcinoma (transitional cell carcinoma, TCC) cells. CDw40 from normal B cells or from the Burkitt lymphoma line Raji showed a characteristic pattern of three bands when analyzed by SDS-PAGE and Western blotting: a main band of 47 kDa, a degradation product of 43 kDa, and a dimer of 85 kDa. The dimer was disrupted by reduction with 2-ME but was reformed spontaneously from the purified monomers under nonreducing conditions. CDw40 from two bladder cancer cell lines gave a similar pattern but formed little or no dimer. Thirty amino acids of the amino terminal end of CDw40 from Raji and 22 amino acids of that from TCC cells (HU549) were sequenced. The sequences were unusually rich in cysteines and differed only in that the cysteine in position 6 in Raji CDw40 had been replaced by glutamine in HU549. In addition there were two conservative changes in positions 15 and 19. Taken together these results show that CDw40 derived from B cells or from TCC cells are the same or closely related molecules. Comparisons of the amino acid sequence and biochemical characteristics of CDw40 with proteins having receptor functions indicated a close structural resemblance of CDw40 to the nerve growth factor-receptor.
Ag CDw40（p50，Bp50）是一种磷蛋白，表达于B淋巴细胞表面以及某些非造血源性恶性细胞类型表面。已证明针对该抗原的抗体可作为B细胞的强效共刺激原。为了阐明该抗原的功能，我们现在研究了其一些生化特性以及B细胞来源的CDw40与膀胱癌细胞（移行细胞癌，TCC）来源的CDw40之间的关系。通过SDS-PAGE和蛋白质印迹分析，正常B细胞或伯基特淋巴瘤细胞系Raji来源的CDw40呈现出三条带的特征模式：一条47 kDa的主带、一条43 kDa的降解产物带以及一条85 kDa的二聚体带。该二聚体在用2-巯基乙醇还原时被破坏，但在非还原条件下可从纯化的单体自发重新形成。来自两个膀胱癌细胞系的CDw40呈现出类似的模式，但几乎不形成或不形成二聚体。对Raji来源的CDw40的氨基末端30个氨基酸以及TCC细胞（HU549）来源的CDw40的22个氨基酸进行了测序。这些序列富含半胱氨酸，不同之处仅在于Raji CDw40第6位的半胱氨酸在HU549中被谷氨酰胺取代。此外，在第15和19位有两个保守变化。综合这些结果表明，B细胞来源或TCC细胞来源的CDw40是相同或密切相关的分子。将CDw40的氨基酸序列和生化特性与具有受体功能的蛋白质进行比较表明，CDw40与神经生长因子受体在结构上有密切相似性。
