Detection of cGMP dependent protein kinase isozymes by specific antibodies


Correspondence to F. Hofmann, Institut für Pharmakologie und Toxikologie, Technische Universität München, Biedersteiner Strasse 29, W-8000 München 40, Federal Republic of Germany


Two isozymes of cGMP-dependent protein kinase (cGMP kinase) have been identified. Polyclonal antibodies were developed which recognize both isozymes or specifically the Iα and Iβ isoform. The specificity of these antibodies was verified by using the recombinant or purified Iα and Iβ isozymes. The antibodies cross-reacted with the purified isozymes of cGMP kinase from bovine tracheal smooth muscle. The tissue concentration of cGMP kinase was determined by ELISA. High concentrations (> 10 pmol/g wet tissue) were present in bovine lung, rumen, trachea, aorta, uterus and stomach. The tissue distribution of the isozymes Iα and Iβ was investigated by immunoblots using crude extracts of the different tissues. The Iβ-specific antibody yielded strong signals with extracts of trachea, aorta, stomach and uterus, whereas heart, cerebellum and lung apparently contain mainly the Iα isozyme