A key player of this restriction is the sterile alpha motif-hydroxylase domain 1 protein (SAMHD1, [6 ,7 ,14 ], a dGTP-dependent deoxynucleotide triphosphohydrolase that maintains dNTPs at concentrations that are limiting for efficient reverse transcription [5 ,16 ,17 ,18 ,19 ,20 ]).
Source: wiktionary