A cysteine residue located in the transmembrane domain of CD44 is important in binding of CD44 to hyaluronic acid.
A cysteine residue located in the transmembrane domain of CD44 is important in binding of CD44 to hyaluronic acid.
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DOI：
10.1084/jem.183.5.1987
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发表时间：
1996-05-01
期刊：
影响因子：
--
通讯作者：
Sy MS
中科院分区：
文献类型：
--
作者：
Liu D;Sy MS
人CD44蛋白的跨膜结构域和胞浆结构域中有两个半胱氨酸残基。这两个半胱氨酸在所有已知的哺乳动物 CD44 蛋白中都是保守的。这些半胱氨酸残基的功能尚不清楚。使用位点特异性诱变来产生缺乏这些半胱氨酸残基之一或两者的CD44突变蛋白。将野生型CD44和突变型CD44基因转染至CD44-Jurkat细胞中以建立稳定的转染子。这些转染子用于研究这两个半胱氨酸残基对于 CD44(H) 与荧光素偶联透明质酸 (F-HA) 的结合是否重要。带有野生型CD44的Jurkat转染子不结合F-HA，除非它们在体外用固定化抗CD3单克隆抗体刺激。抗CD3抗体还刺激Jurkat CD44.C295A转染子中F-HA的结合，其中细胞质半胱氨酸残基已被丙氨酸取代。相比之下，抗CD3抗体未能刺激Jurkat转染子(CD44.C286A)和Jurkat转染子CD44.2C2A中F-HA的结合，其中跨膜结构域半胱氨酸286已被丙氨酸取代，而Jurkat转染子CD44.2C2A中两个半胱氨酸残基均已改变。还可以在 Jurkat 野生型 CD44 和 Jurkat CD44.C295A 转染子中用单克隆抗 CD44 抗体 (F-44-10-2) 诱导结合，但在 CD44 中则不然。 C286A转染子。这些结果提供证据表明CD44的跨膜结构域，更具体地跨膜结构域中的半胱氨酸残基，对于激活诱导的和抗CD44抗体诱导的可溶性HA的结合都很重要。
In the transmembrane domain and cytoplasmic domain of human CD44 protein there are two cysteine residues. These two cysteines are conserved in all known mammalian CD44 proteins. The functions of these cysteine residues are not known. Site-specific mutagenesis was used to create CD44 mutant proteins lacking either one or both of these cysteine residues. Wild-type CD44 and mutant CD44 genes were transfected into CD44- Jurkat cells to establish stable transfectants. These transfectants were used to study whether these two cysteine residues are important in the binding of CD44(H) to fluorescein- conjugated hyaluronic acid (F-HA). Jurkat transfectant bearing wild- type CD44 did not bind F-HA, unless they were stimulated in vitro with immobilized anti-CD3 monoclonal antibody. Anti-CD3 antibody also stimulated the binding of F-HA in Jurkat CD44.C295A transfectant in which the cytoplasmic cysteine residue has been replaced with alanine. In contrast, anti-CD3 antibody failed to stimulate the binding of F-HA in Jurkat transfectant (CD44.C286A), in which the transmembrane domain cysteine 286 has been replaced with an alanine, and in Jurkat transfectant CD44.2C2A, in which both of the cysteine residues have been altered. Binding can also be induced with a monoclonal anti-CD44 antibody (F-44-10-2) in Jurkat wild-type CD44 and Jurkat CD44.C295A transfectants but not in CD44. C286A transfectant. These results provide evidence that the transmembrane domain of CD44, more specifically the cysteine residue in the transmembrane domain, is important for both activation-induced and anti-CD44 antibody-induced binding of soluble HA.