<p>Proteins with a small GTP-binding domain include Ras, RhoA, Rab11, translation elongation factor G, translation initiation factor IF-2, tetratcycline resistance protein TetM, CDC42, Era, ADP-ribosylation factors, tdhF, and many others [<cite idref="PUB00015117"/>]. In some proteins the domain occurs more than once. Among them there is a large number of small GTP-binding proteins and related domains in larger proteins. Note that the alpha chains of heterotrimeric G proteins are larger proteins in which the NKXD motif is separated from the GxxxxGK[ST] motif (P-loop) by a long insert and are not easily detected by this model.</p>