The function of ENSG00000172594 (SMPDL3A, sphingomyelin phosphodiesterase acid like 3A) is as follows. Cyclic-nucleotide phosphodiesterase that acts as a negative regulator of innate immunity by mediating degradation of 2',3'-cGAMP, thereby inhibiting the cGAS-STING signaling (PubMed:37890481). Specifically linearizes 2',3'-cGAMP into 2'5'-bond pGpA and further hydrolyzes pGpA to produce GpA (PubMed:37890481). Also has in vitro nucleotide phosphodiesterase activity with nucleoside triphosphates, such as ATP (PubMed:25288789, PubMed:26783088). Has in vitro activity with p-nitrophenyl-TMP (PubMed:25288789). Has lower activity with nucleoside diphosphates, and no activity with nucleoside monophosphates (PubMed:25288789, PubMed:26783088, PubMed:28104755). Has in vitro activity with CDP-choline, giving rise to CMP and phosphocholine. Has in vitro activity with CDP-ethanolamine (PubMed:26783088). Does not have sphingomyelin phosphodiesterase activity (PubMed:25288789, PubMed:26783088). {ECO:0000269|PubMed:25288789, ECO:0000269|PubMed:26783088, ECO:0000269|PubMed:28104755, ECO:0000269|PubMed:37890481}.