Glycerophosphodiester phosphodiesterase domain of mammalian glycerophosphodiester phosphodiesterase GDE3 and similar proteins
This subfamily corresponds to the glycerophosphodiester phosphodiesterase domain (GDPD) present in mammalian GDE3 (also known as glycerophosphodiester phosphodiesterase domain-containing protein 2 (GDPD2), Osteoblast differentiation promoting factor) and their metazoan homologs. Mammalian GDE3 is a transmembrane protein specifically expressed in bone tissues and spleen. It is a mammalian homolog of bacterial glycerophosphodiester phosphodiesterases (GP-GDEs, EC 3.1.4.46), which catalyzes the hydrolysis of various glycerophosphodiesters, and produce sn-glycerol-3-phosphate (G3P) and the corresponding alcohols. Mammalian GDE3 has been characterized as glycerophosphoinositol inositolphosphodiesterase (EC 3.1.4.43) that selectively hydrolyzes extracellular glycerophosphoinositol (GPI) to generate inositol 1-phosphate (Ins1P) and glycerol. Mammalian GDE3 functions as an inducer of osteoblast differentiation. It also plays a critical role for actin cytoskeletal modulation. The catalytic activity of GDPD domain is essential for mammalian GDE3 cellular function.
Comment:The catalytic mechanism of glycerophosphodiester phosphodiesterases is based on the metal ion-dependent general acid-base reaction.
Comment:Based on structure evidence and site-directed mutagenesis of Thermoanaerobacter tengcongensis glycerophosphodiester phosphodiesterase, the catalytic site consists of two conserved histidine residues which serve as general acid and general base in catalyzing the hydrolysis of the 3'-5' phosphodiester bond.
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