Alternative translation initiation further increases the molecular and functional diversity of ion channels.

摘要

The diversity of ion channels is attributed to the different subunit genes expressed in a given cell, to alternative splicing, to hetero-multimerization and to post-translational modifications. Another mechanism, called alternative translation initiation (ATI), was recently shown to further increase the molecular and functional complexity of K~+ channels (Thomas et al. 2008; and see Simkin et al. 2008). The genes produce two or more versions of the encoded proteins from a single mRNA, and the shorter version, initiated from a downstream in-frame start codon, lacks the N-terminal fragment of the full-length isoform version. ATI is thought to occur when the ribosome skips the first translation initiation site because of a non-optimal sequence (Kozak sequence) near the initiation site and moves down to the next AUG codon to initiate translation of the protein (Fig. 1).