PDE1
PDE1 (phosphodiesterase type 1) is a phosphodiesterase enzyme also known as calcium- and calmodulin-dependent phosphodiesterase. It is one of the 11 families of phosphodiesterase (PDE1-PDE11). PDE1 has three subtypes, PDE1A, PDE1B and PDE1C which divide further into various isoforms. The various isoforms exhibit different affinities for cAMP and cGMP.
The existence of the Ca2+-stimulated PDE1 was first demonstrated by Cheung (1970), Kakiuchi and Yamazaki (1970) as a result of their research on bovine brain and rat brain respectively. It has since been found to be widely distributed in various mammalian tissues as well as in other eukaryotes. It is now one of the most intensively studied member of the PDE superfamily of enzymes, which today represents 11 gene families, and the best characterized one as well.
Further researches in the field along with increased availability of monoclonal antibodies have shown that various PDE1 isozymes exist and have been identified and purified. It is now known that PDE1 exists as tissue specific isozymes.
The PDE1 isozyme family belongs to a Class I enzymes, which includes all vertebrate PDEs and some yeast enzymes. Class I enzymes all have a catalytic core of at least 250 amino acids whereas Class II enzymes lack such a common feature.
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