CALP1

CALP1 is an 8-residue calcium-like peptide that interacts with an EF hand motif based on the troponin C superfamily calcium binding site.[1] It binds to calmodulin (Kd = 88 µM) and activates phosphodiesterase in the presence of calmodulin and absence of calcium. CALP1 also acts as a cell-permeable inhibitor of calcium influx through glutamate receptor channels in cultured rat neocortical neurons thereby inhibiting excitatory cytotoxicity (IC50 = 52.48 µM) and apoptosis (IC50 = 44.78 µM).[2] CALP1 (1 mg/kg) pretreatment prevents increases in lung alveolar inflammatory cells after six, but not 24, hours in sensitized guinea pigs challenged with ovalbumin in a model of allergic asthma.[3] It also decreases radical production induced by phorbol 12-myristate 13-acetatein broncho-alveolar lavage cells after six and 24 hours and dose-dependently decreases histamine-induced hyperresponsiveness in isolated guinea pig tracheal rings.

Reference:
[1]. Villain, M., Jackson, P.L., Manion, M.K., et al. De novo design of peptides targeted to the EF hands of calmodulin. J. Biol. Chem. 275(4), 2676-2685 (2000).
[2]. Manion, M.K., Su, Z., Villain, M., et al. A new type of Ca2+ channel blocker that targets Ca2+ sensors and prevents Ca2+-mediated apoptosis. FASEB J. 14(10), 1297-1306 (2000).
[3]. Ten Broeke, R., Brandhorst, M.C., Leusink-Muis, T., et al. Ca2+ sensors modulate asthmatic symptoms in an allergic model for asthma. Eur. J. Pharmacol. 476(1-2), 151-157 (2003).