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标题：Cloning and characterization of two splice variants of human phosphodiesterase 11A
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作者：Joanna M. Hetman ; Nicola Robas ; Rhona Baxendale 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2000
卷号：97
期号：23
页码：12891-12895
DOI：10.1073/pnas.200355397
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Phosphodiesterase 11A (PDE11A) is a recently identified family of cAMP and cGMP hydrolyzing enzymes. Thus far, a single splice variant designated as PDE11A1 has been reported. In this study, we identify and characterize two additional splice variants of PDE11A, PDE11A2 and PDE11A3. The full-length cDNAs are 2,141 bp for PDE11A2 and 2205 bp for PDE11A3. The ORF of PDE11A2 predicts a protein of 576 aa with a molecular mass of 65.8 kDa. The ORF of PDE11A3 predicts a protein of 684 aa with a molecular mass of 78.1 kDa. Comparison of the PDE11A2 sequence with that of PDE11A1 indicates an additional 86 aa at the N terminus of PDE11A2. Part of this sequence extends the potential cGMP binding region (GAF domain) present in PDE11A1. Compared with PDE11A2, PDE11A3 has an additional 108 N-terminal amino acids. Sequence analysis of PDE11A3 indicates the presence of another GAF domain in this region. This diversification of regulatory sequences in the N-terminal region of PDE11A splice variants suggests the interesting possibility of differential regulation of these enzymes. Recombinant PDE11A2 and -A3 proteins expressed in the Baculovirus expression system have the ability to hydrolyze both cAMP and cGMP. The Km values for cAMP hydrolysis are 3.3 {micro}M and 5.7 {micro}M for PDE11A2 and PDE11A3, respectively. The Km values for cGMP hydrolysis are 3.7 {micro}M and 4.2 {micro}M for PDE11A2 and PDE11A3, respectively. Both PDEs showed a Vmax ratio for cAMP/cGMP of approximately 1.0. PDE11A2 is sensitive to dipyridamole, with an IC50 of 1.8 {micro}M, and to zaprinast, with an IC50 of 28 {micro}M. PDE11A3 demonstrated similar pattern of inhibitor sensitivity with IC50 values of 0.82 and 5 {micro}M for dipyridamole and zaprinast, respectively.