Deoxynucleoside triphosphate triphosphohydrolase SAMHD1 is a ~72 kDa protein. Protein that acts both as a host restriction factor involved in defense response to virus and as a regulator of DNA end resection at stalled replication forks. Has deoxynucleoside triphosphate (dNTPase) activity, which is required to restrict infection by viruses, such as HIV-1: dNTPase activity reduces cellular dNTP levels to levels too low for retroviral reverse transcription to occur, blocking early-stage virus replication in dendritic and other myeloid cells. Likewise, suppresses LINE-1 retrotransposon activity. Not able to restrict infection by HIV-2 virus; because restriction activity is counteracted by HIV-2 viral protein Vpx. In addition to virus restriction, dNTPase activity acts as a regulator of DNA precursor pools by regulating dNTP pools. 5. White, TE. et al. (2013) Cell host & microbe 13, 441-51. PMID: 236011068. Tang, C. et al. (2015) The Journal of biological chemistry 290, 26352-9. PMID: 262947629. Arnold, LH. et al. (2015) PLoS pathogens 11, e1005194. PMID: 2643120010. White, TE. et al. (2017) Human mutation 38, 658-668. PMID: 28229507 | 
