The ribosomal stalk also known as P-stalk is a pentameric complex composed of universally conserved proteins. The stalk is part of the GTPase Associated Centre (GAC) and represents one of its main functional elements. The role of the P-stalk within GAC is to recruit translational GTPases, such as elongation factor 2 (EF2) and stimulation of factor-dependent GTP hydrolysis. Interestingly, a family of ribosomal inactivating proteins (RIP) engages with P-stalk to activate its mechanism of inhibition. For example, the interaction of Ricin (type II RIP) with ribosomal stalk leads to depurination of a sarcin-ricin loop and translation stalling.

protein – protein interaction | ribosomal proteins | P-stalk | ricin | P1-P2 | MO-P-034