Identity of a membrane-bound vasoactive intestinal peptide-binding protein with calmodulin.
A vasoactive intestinal peptide (VIP)-binding protein purified from guinea pig lung membranes (p18) was digested with trypsin, and the amino acid sequence of the peptide fragments was determined. The sequence of six tryptic fragments of p18 was identical with subsequences present in mammalian calmodulin. Authentic porcine brain calmodulin and p18 co-migrated on an sodium dodecyl sulfate-electrophoresis gel and displayed identical chromatographic behavior on a reverse phase high performance liquid chromatography column. The VIP-binding properties of p18 and calmodulin were indistinguishable. Both proteins displayed saturable and apparent high affinity binding of VIP, evidenced by potent inhibition of complexation with [Tyr10-125I]VIP by unlabeled VIP (IC50 = 6.0-8.1 nM). Rat growth hormone releasing factor and a C terminally extended form of VIP ([Leu17]VIP-GKR) also displayed potent inhibition of the binding (IC50 = 6.4 and 4 nM, respectively). These neuropeptides are potential modulators of calmodulin function.
Stallwood
D
D
Department of Anesthesia, University of Nebraska Medical Center, Omaha 68198-4455.
Brugger
C H
CH
Baggenstoss
B A
BA
Stemmer
P M
PM
Shiraga
H
H
Landers
D F
DF
Paul
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D006168:Guinea Pigs; D008168:Lung / Q000378:metabolism; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D011485:Protein Binding; D012995:Solubility; D013552:Swine; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism*
D002147:Calmodulin; D046911:Macromolecular Substances; D014660:Vasoactive Intestinal Peptide; D002118:Calcium