LYMPHOCYTE SPECIFIC HETEROGENEITY IN THE RAT LEUKOCYTE COMMON ANTIGEN (T200) IS DUE TO DIFFERENCES IN POLYPEPTIDE SEQUENCES NEAR THE NH2-TERMINUS
LYMPHOCYTE SPECIFIC HETEROGENEITY IN THE RAT LEUKOCYTE COMMON ANTIGEN (T200) IS DUE TO DIFFERENCES IN POLYPEPTIDE SEQUENCES NEAR THE NH2-TERMINUS
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DOI：
10.1002/j.1460-2075.1987.tb02362.x
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发表时间：
1987-05-01
期刊：
影响因子：
11.4
通讯作者：
WILLIAMS, AF
中科院分区：
文献类型：
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作者：
BARCLAY, AN;JACKSON, DI;WILLIAMS, AF
白细胞共同抗原(L-CA，T200或CD45)由一组高度糖化的糖蛋白家族组成，表观MR为180,000-240,000，仅限于淋巴样细胞和髓系细胞。不同表观MR、抗原性和糖基化程度不同的L-CA表达于不同的淋巴细胞类型。一种称为MRC ox-22的特定抗原决定簇特别令人感兴趣，因为它区分了两组具有不同功能的T辅助细胞。从不同的L-CA基因克隆的序列中，我们得出结论：L-CA至少存在四种形式的序列异质性，其序列在1118-1250个氨基酸范围内。所有的序列变异都发生在从NH2末端的6个残基开始的点上，所有形式的最后1112个残基是相同的。其中两个变异体可以与抗原变异直接相关，因为它们包括为携带MRC ox-22决定簇的多肽确定的序列。对L-CA胸腺细胞糖肽的分析表明，在14个可能的N-糖基化位点中只有一个是非糖化的，所有的O-糖基化都在前32个氨基酸范围内。较长形式的额外蛋白质序列也暗示了广泛的O-糖基化。
The leucocyte-common antigen (L-CA, T200 or CD45) consists of a family of heavily glycosylated glycoproteins of apparent Mr 180,000-240,000 which are restricted to lymphoid and myeloid cells. Forms of L-CA which differ in their apparent Mr, antigenicity and glycosylation are expressed on different lymphocyte types. One specific antigenic determinant called MRC OX-22 is of particular interest because it distinguishes two sets of T helper cells that have different functions. From the sequence of different L-CA cDNA clones we now conclude that there is sequence heterogeneity such that at least four forms of L-CA exist with sequences in the range 1118-1250 amino acids. All the sequence variation occurs at a point starting 6 residues from the NH2-terminus and the last 1112 residues of all forms are identical. Two of the variants can be directly related to the antigenic variation because they include sequence that was determined for peptide that carries the MRC OX-22 determinant. Analysis of glycopeptides from thymocyte L-CA identified only one non-glycosylated position out of 14 possible N-glycosylation sites and established that all O-glycosylation was within the first 32 amino acids. The extra protein sequence in the longer forms was also suggestive of extensive O-glycosylation.