MOLECULAR-CLONING OF THE RAT ADIPOCYTE HORMONE-SENSITIVE CYCLIC GMP-INHIBITED CYCLIC-NUCLEOTIDE PHOSPHODIESTERASE

Two distinct but related cGMP-inhibited cyclic nucleotide phosphodiest erase (cGI PDE) cDNAs were cloned from rat adipose tissue cDNA librari es. The open reading frame (3324 base pairs) of RcGIP1 encodes 1108 am ino acids, including a hydrophobic membrane-association domain in the NH2-terminal portion and, in the COOH-terminal portion, a putative cat alytic domain conserved among all mammalian PDEs which is preceded by a putative regulatory domain that contains three consensus cAMP-depend ent protein kinase phosphorylation sites and followed by a hydrophilic COOH-terminal domain. The carboxyl-terminal portion including the con served domain was expressed as a glutathione S-transferase fusion prot ein and exhibited cAMP PDE activity which was inhibited by cilostamide , a specific cGI PDE inhibitor. RcGIP1 cDNA hybridizes strongly with R NA from isolated adipocytes, and its mRNA increases dramatically durin g differentiation of 3T3-L1 adipocytes. The deduced sequence of the se cond partial cDNA clone (RcGIP2 clone 53B) is highly homologous to the corresponding region of human cardiac cGI PDE cDNA. RcGIP2 cDNA hybri dized strongly with rat cardiac tissue RNA and weakly if at all with R NA from rat adipocytes or 3T3-L1 fibroblasts or adipocytes. We suggest that RcGIP1 represents the hormone-sensitive, membrane-associated rat adipocyte cGI PDE and RcGIP2, a cGI PDE from vascular elements in rat adipose tissue.