Js. Davidson et al., IDENTIFICATION OF N-GLYCOSYLATION SITES IN THE GONADOTROPIN-RELEASING-HORMONE RECEPTOR - ROLE IN RECEPTOR EXPRESSION BUT NOT LIGAND-BINDING, Molecular and cellular endocrinology, 107(2), 1995, pp. 241-245
The asparagine residues of the three N-glycosylation consensus sequenc
es in the mouse gonadotropin-releasing hormone receptor were mutated t
o determine which residues were glycosylated and the function of glyco
sylation. Photoaffinity labelled Gln(4) and Gln(18) receptor mutants e
xhibited lower apparent molecular weight on SDS polyacrylamide gel ele
ctrophoresis, while the Gln(102) receptor showed wildtype mobility. Th
is indicates that the receptor is glycosylated at Asn(4) and Asn(18) b
ut not at Asn(102). Binding affinities of all the mutant receptors wer
e normal, indicating that carbohydrate moieties are not involved in li
gand binding interactions. However, expression of the Gln(4) and Gln(1
8) receptors were substantially decreased, indicating a role for glyco
sylation in receptor expression or stability. All the glycosylation si
te mutants were capable of normal signal transduction, as indicated by
their ability to stimulate inositol phosphate production.