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Formation of a Disulfide Bond in the Immunoglobulin Domain of the Myelin P 0 Protein Is Essential for Its Adhesion
Author(s) -
Zhang Kejia,
Filbin Marie T.
Publication year - 1994
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1994.63010367.x
Subject(s) - immunoglobulin domain , chinese hamster ovary cell , immunoglobulin superfamily , transfection , cell adhesion molecule , complementary dna , microbiology and biotechnology , chemistry , cell adhesion , antibody , biology , biochemistry , cell , receptor , gene , genetics
It is widely accepted, although never demonstrated, that the formation of a disulfide bond in the majority of immunoglobulin (Ig)‐like domains stabilizes their final conformation and thus is essential to their functioning as adhesion/recognition molecules. The myelin P 0 protein, which has been shown directly to behave as a homophilic adhesion molecule, contains a single Ig‐like domain, stabilized by a putative Cys 21 ‐Cys 98 disulfide bond. To test if this bond is indeed necessary to the adhesive function of P 0 , the nucleotides in the P 0 cDNA coding for Cys 21 were altered to code for an alanine. The mutated P 0 cDNA was transfected into Chinese hamster ovary cells, expression of the mutated P 0 protein was characterized, and the adhesiveness of Cys 21 ‐mutated P 0 ‐expressing cells and that of cells expressing equivalent surface amounts of the unmutated protein were compared. It was found, as we previously reported, that incubation of a single cell suspension of the unmutated P 0 ‐expressing cells resulted in the rapid formation of large aggregates. In contrast, after a similar incubation the cells expressing the Cys 21 ‐mutated P 0 were still mostly single cells, a result indistinguishable from that observed with the control transfected cells. This suggests that the P 0 protein, when mutated at Cys 21 , does not behave as a homophilic adhesion molecule, which in turn implies that the formation of an Ig domain disulfide bond is essential to the functioning of this molecule.