ENTRY INTO THE SECRETORY SYSTEM - THE ROLE OF MESSENGER-RNA LOCALIZATION

In addition to protein targeting mechanisms, proteins may also be targ eted to specific subcellular compartments by localization of their mRN As. mRNA localization, which is a more cost-effective mechanism than p rotein targeting, can control assembly of macromolecular structures wi thin the cell, aid in the formation of endoplasmic reticulum subdomain s, facilitate protein localization in the endomembrane system and cont rol gene expression. in addition, mRNA localization in plants is likel y to be an important mechanism for controlling intercellular communica tion not only between adjacent cells but those separated by relatively long distances. Although mRNAs can be localized by different mechanis ms, evidence gathered to date implicate the role of cytoskeletal eleme nts, microfilaments and microtubules, in the transport and anchoring o f RNAs to specific subcellular locations within the cell.