Photoaffinity labelling of the oxytocin receptor in plasma membranes from rat mammary gland |
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Authors: | M Müller M S Soloff F Fahrenholz |
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Institution: | Max-Planck-Institut für Biophysik, Frankfurt, FRG. |
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Abstract: | Plasma membranes from rat mammary gland containing a high concentration of 3H]oxytocin binding sites (2.8 pmol/mg protein) were used for photoaffinity labelling experiments. Competitive binding experiments show that these receptors bind with high affinity the specific oxytocin agonist Thr4, Sar7]oxytocin and the analogue of 1-deamino-8-lysine]vasopressin containing a photoreactive azidobenzoyl group (Abz) at the side chain of lysine. The tritium-labelled (50 Ci/mol) photoreactive analogue incorporated into a membrane protein with an apparent relative molecular mass of 65,000 +/- 3000 Da (n = 16). The labelling of this protein was completely suppressed by an excess of oxytocin. |
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