Structural determinants for binding to CGRP receptors expressed by human SK-N-MC and Col 29 cells: studies with chimeric and other peptides

Br J Pharmacol. 1998 Aug;124(8):1659-66. doi: 10.1038/sj.bjp.0702032.

Abstract

Structure-activity relationships for the binding of human alpha-calcitonin gene-related peptide 8-37 (halphaCGRP8-37) have been investigated at the CGRP receptors expressed by human SK-N-MC (neuroblastoma) and Col 29 (colonic epithelia) cells by radioligand binding assays and functional assays (halphaCGRP stimulation of adenylate cyclase). On SK-N-MC cells the potency order was halphaCGRP8-37 > halphaCGRP19-37 = AC187 > rat amylin8-37 > halpha[Tyr0]-CGRP28-37 (apparent pKBs of 7.49+/-0.25, 5.89+/-0.20, 6.18+/-0.19, 5.85+/-0.19 and 5.25+/-0.07). The SK-N-MC receptor appeared CGRP1-like. On Col 29 cells, only halphaCGRP8-37 of the above compounds was able to antagonize the actions of halphaCGRP (apparent pKB=6.48+/-0.28). Its receptor appeared CGRP2-like. halpha[Ala11,18]-CGRP8-37, where the amphipathic nature of the N-terminal alpha-helix has been reduced, bound to SK-N-MC cells a 100 fold less strongly than halphaCGRP8-37. On SK-N-MC cells, halphaCGRP8-18,28-37 (M433) and mastoparan-halphaCGRP28-37 (M432) had apparent pKBs of 6.64+/-0.16 and 6.42+/-0.26, suggesting that residues 19-27 play a minor role in binding. The physico-chemical properties of residues 8-18 may be more important than any specific side-chain interactions. M433 was almost as potent as halphaCGRP8-37 on Col 29 cells (apparent pKB=6.17+/-0.20). Other antagonists were inactive.

MeSH terms

  • Adenylyl Cyclases / metabolism
  • Amino Acid Sequence
  • Amyloid / chemistry
  • Amyloid / metabolism
  • Animals
  • Calcitonin Gene-Related Peptide / pharmacology
  • Calcitonin Gene-Related Peptide Receptor Antagonists
  • Cell Line
  • Chemical Phenomena
  • Chemistry, Physical
  • Cyclic AMP / metabolism
  • Humans
  • Islet Amyloid Polypeptide
  • Molecular Sequence Data
  • Neuropeptides / chemistry*
  • Neuropeptides / metabolism*
  • Peptide Fragments / pharmacology
  • Radioligand Assay
  • Rats
  • Receptors, Calcitonin Gene-Related Peptide / chemistry*
  • Receptors, Calcitonin Gene-Related Peptide / metabolism*
  • Recombinant Fusion Proteins / chemistry*
  • Recombinant Fusion Proteins / metabolism*
  • Structure-Activity Relationship
  • Tumor Cells, Cultured

Substances

  • Amyloid
  • Calcitonin Gene-Related Peptide Receptor Antagonists
  • Islet Amyloid Polypeptide
  • Neuropeptides
  • Peptide Fragments
  • Receptors, Calcitonin Gene-Related Peptide
  • Recombinant Fusion Proteins
  • calcitonin gene-related peptide (8-37)
  • Cyclic AMP
  • Adenylyl Cyclases
  • Calcitonin Gene-Related Peptide