Binding of CGRP analogs and their effect on adenylate cyclase activity in porcine iris-ciliary body.
The structure-activity relationship of the calcitonin gene-related peptide (CGRP) in the porcine iris-ciliary body was studied using different CGRP analogs. The receptor binding affinity is located mainly in the carboxyterminal end of the CGRP peptide while the ability to stimulate adenylate cyclase (AC) enzyme is mainly in the aminoterminal end of the peptide. The binding of CGRP analogs was also found to be temperature-dependent. Changes in the alpha-helical region or in the beta-turn, as well as replacements of threonine-4, asparagine-25 or asparagine-26, reduce the binding affinity already at +4 degrees C. Truncated aminoterminus, changes in the loop region between cysteines 2 and 7, and especially in threonine 6, have for their part an important role in maintaining AC-stimulating activity.
Heino
P
P
Preclinical Research, Santen Oy, Tampere, Finland.
Oksala
O
O
Palkama
A
A
Valo
T
T
Vihavainen
S
S
Koskinen
A
A
Uusitalo
H
H
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D015740:Calcitonin Gene-Related Peptide / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology*; D002924:Ciliary Body / Q000187:drug effects / Q000378:metabolism*; D006358:Hot Temperature; D007498:Iris / Q000187:drug effects / Q000378:metabolism*; D008969:Molecular Sequence Data; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013552:Swine
D018015:Receptors, Calcitonin Gene-Related Peptide; D000262:Adenylyl Cyclases; D015740:Calcitonin Gene-Related Peptide