- Endogenous type II cGMP-dependent protein kinase exists as a dimer in membranes and can Be functionally distinguished from the type I isoforms. Vaandrager, A.B., Edixhoven, M., Bot, A.G., Kroos, M.A., Jarchau, T., Lohmann, S., Genieser, H.G., de Jonge, H.R. J. Biol. Chem. (1997)