Retinoic acid receptor in the chick limb buds in the early developmental stages

Two retinoic acid-binding proteins, a high molecular weight one (90-100 kDa) (peak A) and CRABP (peak B), were obtained on gel filtration column chromatography of extracts of limb buds of chick embryos. The presence of a retinoic acid receptor (RAR) (45 kDa) and the absence of chick-CRABP type II (16.2 kDa) in the peak A fractions suggested that the 45 kDa RAR forms a homo- or hetero-dimeric structure (90-100 kDa) with other RARs or other nuclear proteins, but not with chick-CRABP type II, in the limb buds of chick embryos. We also demonstrated that there were no significant differences in the amount of RAR in the anterior, middle and posterior parts of limb buds (stages 23-25).