Lin C S, Lau A, Tu R, Lue T F
Knuppe Molecular Urology Laboratory, Department of Urology, University of California, San Francisco, California 94143-1695, USA.
Biochem Biophys Res Commun. 2000 Feb 16;268(2):628-35. doi: 10.1006/bbrc.2000.2187.
Inhibition of cGMP-specific phosphodiesterase type V (PDE5) has been shown to improve penile erection in patients with erectile dysfunction. We report here the cloning of three PDE5 isoforms from human penile tissues. Two of the isoforms were identical to PDE5A1 and PDE5A2, respectively, which had been isolated from nonpenile tissues. The third isoform was novel and hence called PDE5A3. The deduced amino acid sequence of PDE5A3 was the same as the C-terminal 823-residue sequence of PDE5A1 and PDE5A2. While PDE5A1 and A2 isoforms were expressed in all tissues examined, the A3 isoform was confined to tissues with a smooth muscle or cardiac muscle component. When expressed in COS-7 cells, PDE5A1, A2, and A3 isoforms had similar cGMP-catalytic activities with K(m) of 6.2, 5.75, and 6.06 microM, respectively. Their cGMP-catalytic activities were inhibited by zaprinast with IC(50) values of 3.2 microM, 1.3 microM, and 1.6 microM, respectively, and by sildenafil with IC(50) of 28, 14, and 13 nM, respectively.
已证明抑制5型环鸟苷酸特异性磷酸二酯酶（PDE5）可改善勃起功能障碍患者的阴茎勃起。我们在此报告从人阴茎组织中克隆出三种PDE5亚型。其中两种亚型分别与从非阴茎组织中分离出的PDE5A1和PDE5A2相同。第三种亚型是新发现的，因此称为PDE5A3。PDE5A3推导的氨基酸序列与PDE5A1和PDE5A2的C端823个残基序列相同。虽然PDE5A1和A2亚型在所有检测的组织中均有表达，但A3亚型局限于含有平滑肌或心肌成分的组织。当在COS-7细胞中表达时，PDE5A1、A2和A3亚型具有相似的环鸟苷酸催化活性，其米氏常数（K(m)）分别为6.2、5.75和6.06微摩尔。它们的环鸟苷酸催化活性分别被扎普司特抑制，其半数抑制浓度（IC(50)）值分别为3.2微摩尔、1.3微摩尔和1.6微摩尔，被西地那非抑制，其IC(50)分别为28、14和13纳摩尔。
