An NTP binding site is a type of binding site found in nucleoside monophosphate (NMP) kinases, N can be adenosine or guanosine. A P-loop is one of the structural motifs common for nucleoside triphosphate (NTP) binding sites, it interacts with the bound nucleotide's phosphoryl groups. For the binding site to be able to bind a nucleotide, the nucleotide must be complex bound to Mg²⁺ og Mn²⁺. Nucleotide binding will cause conformational changes in the protein because the P-loop will bend.