Rp-dGTPαS is the nucleotide substrate of SAMHD1 and is one of the enantiomers of the dNTPαS nucleotide. SAMHD1 is an essential regulator of cellular dNTPs that limits virus ( HIV-1 , etc.) replication in the CD4+ myeloid lineage and resting T cells. The SAMHD1 tetrameric complex catalyzes the hydrolysis of Rp-dGTPαS into 2'-deoxynucleosides and triphosphates.