guanine nucleotide-binding site

Introduction

The best conserved sequence of ATP/GTP binding motifs is a glycine-rich region, which forms a flexible loop between a beta-strand & an alpha-helix. This loop interacts with one of the phosphates of the nucleotide, thus the name 'P-loop'.

Not all ATP- or GTP-binding proteins seem to contain a P-loop. Some proteins contain a completely unrelated ATP-binding site. Other ATP- or GTP-binding proteins contain a flexible loop in a slightly different form than the P-loop.

More general terms

• purine nucleotide-binding site

More specific terms

• GTP-binding site