Monoclonal Antibodies toward Scallop (Patinopecten yessoensis) Testis and Wheat Germ Calmodulins

Abstract

A monoclonal antibody (IM7) toward scallop testis calmodulin and another one (PBE2) toward wheat germ calmodulin were produced. Ca²⁺ was required for IM7 to react with scallop calmodulin. IM7 reacted with the C-terminal region (Asp78-Lys148) of the calmodulin. As observed on competitive ELISA, IM7 reacted with chicken calmodulin, but not with Euglena gracilis or wheat calmodulin, troponin C, myosin light chains, or parvalbumin. It is assumed that the cluster of Thr143, Thr146, and Ser147 in the C-terminal region acts as the antigenic site. IM7 (and Fab of IM7) inhibited the activities of myosin light chain kinase and cAMP-phosphodiesterase. PBE2 reacted with wheat germ calmodulin irrespective of the presence or absence of Ca²⁺, the antigenic site being in the N-terminal region (Alal-Met37). It reacted with wheat and spinach calmodulins, but not with scallop, chicken, or Euglena calmodulin, troponin C, myosin light chains, or parvalbumin. PBE2 had no effect on the activities of myosin light chain kinase and cAMP-phosphodiesterase.