Identification of a Pituitary Growth Hormone-Releasing Peptide (GHRP) Receptor Subtype by Photoaffinity Labeling

摘要: Hexarelin, an analogue of GHRP-6, in which D-Tryptophan has been replaced by its 2-methyl derivative, is known to release growth hormone (GH) vivo and vitro direct action on receptors present anterior pituitary cells. Measurement second messengers (c-AMP, Ca++, IP3) upon somatotrophs stimulation, suggests the existence more than one GHRP receptor subtype. In order document such hypothesis, we have used a new photoactivatable derivative Tyr-Bpa-Ala-Hexarelin. This was shown be fully active GH with neonate rats. Using this ligand, specifically labeled protein apparent Mr 57 000 human, bovine porcine membranes. Hexarelin spiroindoline sulfonamide MK-0677 displaced −57 photolabeled band ED50 6×10−7 M 2×10−5 respectively. Taking into account high efficiency (>60%) covalent incorporation Bpa residue, photoact...