The Saccharomyces cerevisiae poly (A) binding protein (Pab1): Master regulator of mRNA metabolism and cell physiology.

Pab1, the major poly (A) binding protein of the yeast Saccharomyces cerevisiae, is involved in many intracellular functions associated with mRNA metabolism, such as mRNA nuclear export, deadenylation, translation initiation and termination. Pab1 consists of four RNA recognition motifs (RRM), a proline-rich domain (P) and a carboxy-terminal (C) domain. Due to its modular structure, Pab1 can simultaneously interact with poly (A) tails and different proteins that regulate mRNA turnover and translation. Furthermore, Pab1 also influences cell physiology under stressful conditions by affecting the formation of quinary assemblies and stress granules, as well as by stabilizing specific mRNAs to allow translation re-initiation after stress. The main goal of this review is to correlate the structural complexity of this protein with the multiplicity of its functions.