Widespread pre-translational regulation of the inclusion of signal peptides in human proteins.

Signal peptides (SP) are cleavable N-terminal protein motifs used co-translationally for entry of nascent polypeptides into the secretory pathway. Their co-translational cleavage prevents their extensive post-translational regulation and flexibility in their usage is made possible by the control of their inclusion at a pre-translational level. To characterize this regulation on a transcriptome scale, we analyzed the level and mechanisms of inclusion of the 3298 most likely human SP-encoding genes, 47% of which alternatively express their SP.

Extent of pre-translational regulation for the control of nucleocytoplasmic protein localization.

Background: Appropriate protein subcellular localization is essential for proper cellular function. Central to the regulation of protein localization are protein targeting motifs, stretches of amino acids serving as guides for protein entry in a specific cellular compartment. While the use of protein targeting motifs is modulated in a post-translational manner, mainly by protein conformational changes and post-translational modifications, the presence of these motifs in proteins can also be regulated in a pre-translational manner.