The alpha-melanocyte-stimulating hormone (alpha-MSH) receptor of B16 mouse melanoma cells was characterized by photoaffinity labelling using radiolabelled photoactive derivatives of alpha-MSH. A doublet band of 43-46 kDa representing a ligand-receptor complex was identified. A novel adaptation of the streptovadin/biotin-based affinity system was used to isolate the alpha-MSH receptor. A probe was synthesized which contained biotin connected to a photolabelled alpha-MSH analogue via a cleavable disulphide linker and which displayed high affinity for the alpha-MSH receptor. Streptavidin-coated magnetic beads were used as a solid support instead of an affinity column. Covalently linked probe-receptor complexes solubilized in Triton X-100 were equilibrated with the beads, and after magnetic separation and washing, specifically bound complexes were treated with dithiothreitol to cleave the disulphide bridge in the biotin-peptide spacer arm and so release the receptor-ligand complex. The identity of the isolated protein was established by SDS/PAGE analysis. Methods to achieve purification to homogeneity and to allow quantitative isolation of the receptor are discussed.
Isolation and partial purification of a melanocyte-stimulating hormone receptor from B16 murine melanoma cells. A novel approach using a cleavable biotinylated photoactivated ligand and streptavidin-coated magnetic beads
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A R H Ahmed, G W J Olivier, G Adams, M E Erskine, R G Kinsman, S K Branch, S H Moss, L J Notarianni, C W Pouton; Isolation and partial purification of a melanocyte-stimulating hormone receptor from B16 murine melanoma cells. A novel approach using a cleavable biotinylated photoactivated ligand and streptavidin-coated magnetic beads. Biochem J 1 September 1992; 286 (2): 377–382. doi: https://doi.org/10.1042/bj2860377
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