Glycodelin and beta-lactoglobulin, lipocalins with a high structural similarity, differ in ligand binding properties

Human glycodelin, a lipocalin with a high amino acid similarity to beta-lac toglobulins, appears as various glycoforms with different biological activi ties in endometrium (glycodelin-A) and seminal plasma (glycodelin-S). We fo und that the structures of these glycodelins and beta-lactoglobulin are sim ilar. Despite this structural similarity, unlike beta-lactoglobulin, glycod elin-A binds neither retinoic acid nor retinol, It was impossible to detect any endogenous retinoids or steroids in any of the two purified glycodelin s. Both their glycoforms share similar thermodynamic parameters of reversib le denaturation suggesting that native folding of glycodelin-A and glycodel in-S is not influenced by the differences in glycosylation or by ligand bin ding. (C) 1999 Federation of European Biochemical Societies.