Devlin J J, Lew A M, Flavell R A, Coligan J E
EMBO J. 1985 Feb;4(2):369-74. doi: 10.1002/j.1460-2075.1985.tb03638.x.
The DNA sequence of the Q10 genes appears to be highly conserved amongst strains of mice and has only been found to be transcribed in the liver. An examination of the nucleotide sequence of the exon that normally encodes the transmembrane domain of class I molecules suggested that the Q10 gene encodes a secreted protein. We have established this by showing that L cells transformed with an expression vector containing the Q10 gene secrete a class I molecule which was identified with an antiserum raised against a peptide predicted by the Q10 transmembrane exon. Both the L cell-derived Q10 molecule and a class I protein immunoprecipitated from serum with this anti-peptide antiserum have mol. wts. of approximately 38 000; the Q10 molecule secreted by L cells is heterogeneous in mol. wt. This heterogeneity was drastically reduced after endoglycosidase F treatment, suggesting that Q10 molecules secreted into the serum by the liver may be glycosylated differently from those secreted by L cells. Endoglycosidase F treatment of both the L cell and serum forms of the soluble molecule yielded two products with mol. wts. of approximately 32 000 and 35 000; this is consistent with the observation that the predicted Q10 protein sequence has two potential glycosylation sites. In contrast to previous published results, the Q10 molecule reacted with rabbit anti-H-2 antisera which is consistent with its greater than 80% homology to the classical transplantation antigens.
Q10基因的DNA序列在小鼠品系中似乎高度保守，且仅在肝脏中被发现转录。对通常编码I类分子跨膜结构域的外显子核苷酸序列的检查表明，Q10基因编码一种分泌蛋白。我们通过以下方式证实了这一点：用含有Q10基因的表达载体转化的L细胞分泌一种I类分子，该分子可被针对由Q10跨膜外显子预测的肽段产生的抗血清识别。来自L细胞的Q10分子和用这种抗肽抗血清从血清中免疫沉淀的I类蛋白的分子量均约为38000；L细胞分泌的Q10分子在分子量上具有异质性。在内切糖苷酶F处理后，这种异质性大幅降低，这表明肝脏分泌到血清中的Q10分子的糖基化方式可能与L细胞分泌的不同。对内切糖苷酶F处理后的L细胞形式和血清形式的可溶性分子进行分析，均产生了分子量约为32000和35000的两种产物；这与预测的Q10蛋白序列有两个潜在糖基化位点的观察结果一致。与先前发表的结果相反，Q10分子与兔抗H-2抗血清发生反应，这与其与经典移植抗原的同源性大于80%相符。
