Retinoic acid-binding protein: a plasma membrane component

Soluble protein extracts from lyophilized plasma membranes prepared from chick embryo skin and transplantable murine carcinomas were found to contain a specific retinoic acid-binding component. This binding component showed high affinity for biologically active analogs of retinoic acid. The plasma membrane component exhibited similar physicochemical properties to those of the retinoic acid-binding protein described earlier in the cytosol. The protein exhibited mercurial-sensitive thiol functions in ligand binding; the mercurial-inhibition was reversed on treatment with thiol compounds. The plasma membrane binding component may be involved in the cellular uptake of retinoic acid.