Ralph S J, Thomas M L, Morton C C, Trowbridge I S
EMBO J. 1987 May;6(5):1251-7. doi: 10.1002/j.1460-2075.1987.tb02361.x.
Structural variation in the primary structure of human T200 glycoprotein has been detected. Three cDNA variants have been characterized each of which encode T200 molecules that differ in size as a result of sequence differences in their amino-terminal regions. The largest form of the molecule is distinguished from the smallest by an insert of 161 amino acids, after the first eight amino-terminal residues. The other variant has an insert at the same location of 47 amino acids identical to residues 75-121 in the larger insert. Both extra domains are rich in serine and threonine residues and are likely to display multiple O-linked oligosaccharides. These structural variants which probably arise by cell-type-specific alternative splicing provide a molecular basis for the previously observed structural and antigenic heterogeneity of T200 glycoprotein. In addition to the variable amino-terminal region, the external domain of human T200 glycoprotein consists of a second cysteine-rich region of about 400 amino acids, a single transmembrane-spanning region and a large cytoplasmic domain of 707 amino acids shared by all of the structural variants and highly conserved between species. The gene encoding human T200 is located on the long arm of chromosome 1.
已检测到人类T200糖蛋白一级结构中的结构变异。已鉴定出三种cDNA变体，由于其氨基末端区域的序列差异，每种变体编码的T200分子大小不同。该分子的最大形式与最小形式的区别在于，在最初的八个氨基末端残基之后插入了161个氨基酸。另一种变体在相同位置插入了47个氨基酸，与较大插入片段中的75 - 121位残基相同。这两个额外的结构域富含丝氨酸和苏氨酸残基，可能带有多个O - 连接寡糖。这些可能由细胞类型特异性可变剪接产生的结构变体，为先前观察到的T200糖蛋白的结构和抗原异质性提供了分子基础。除了可变的氨基末端区域外，人类T200糖蛋白的外部结构域由一个约400个氨基酸的富含半胱氨酸的第二区域、一个单一的跨膜区域和一个707个氨基酸的大细胞质结构域组成，所有结构变体都共享该细胞质结构域，并且在物种间高度保守。编码人类T200的基因位于1号染色体的长臂上。
