Isolation of Retinoid Receptors from Manimalian Cells

Retinoic acid receptors (RARs) have been detected in nuclear extracis from various cell types on the basis of their ability to bind radiolabeled retinoic acid (1 –3 ). Prior to the isolation of RAR cDNAs in 1987 (4 , 5 ), biochemical evidence for the existence of nuclear retinoic-acid binding proteins distinct from cytoplasmic CRABP had been obtained (1 ). The techniques used in these experiments can be used to study the biochemical properties of the RARs and may also be applicable to the study of the related receptors known as RXRs, which bind 9-cis retinoic acid with high affinity (6 ).