The Fc receptor γ-chain is necessary and sufficient to initiate signalling through glycoprotein VI in transfected cells by the snake C-type lectin, convulxin

Abstract

There is extensive evidence that FcR γ-chain couples to the collagen receptor glycoprotein VI (GPVI) and becomes phosphorylated on tyrosines upon receptor cross-linking. However, it is not established whether this receptor complex is sufficient to initiate the signalling cascade. We transfected GPVI and the FcR γ-chain into the human erythroleukaemia cell line K562, which lacks detectable expression of GPVI and the FcR γ-chain. The results show that GPVI is unable to signal when expressed alone, despite its surface expression, upon stimulation with the snake C-type lectin, convulxin. Coexpression of the FcR γ-chain confers signalling properties on the receptor. Furthermore, cotransfection of the FcR γ-chain and two mutant versions of GPVI shows that the transmembrane arginine and cytoplasmic tail of GPVI are necessary for association with the FcR γ-chain. These results demonstrate that reconstitution of the GPVI-FcR γ-chain complex in cells expressing the necessary signalling network is sufficient to initiate signalling events in response to convulxin and collagen-related peptide.