Post-transcriptional regulation of lipophorin receptors

Abstract

The lipophorin receptors genes generate multiple isoforms with astonishing different functional properties, since only a subset of them is able to mediate neutral lipids uptake. We have previously demonstrated that a 47 amino acids long, differentially spliced complement-type domain (LA-1) is critical for this activity. However, all the isoforms that contain LA-1 also have an atypically long signal peptide (>60 amino acids) of unknown function. Our preliminary data suggests that this long signal peptide allows the translation of some lipophorin receptors isoforms under conditions of cellular stress and generalized inhibition of translation by a novel mechanism that we are currently characterizing. Other Drosophila proteins such as Crumbs and the LDLR family protein Megalin also contain long signal peptides. However, this is the first time a cellular function has been established for them.