Construction Of Three Recombinant GFP Expressing Vectors With Different Signal Sequence And H-FABP Expressing Vector

Export signal sequences target newly synthesized proteins to the endoplasmicreticulum of eukaryotic cells and the plasma membrane of bacteria. All signalsequences contain a hydropHobic core region, but, despite this, they show greatvariation in both overall length and amino acid sequence. Recently, it has becomeclear that this variation allows signal sequences to specify different modes oftargeting and membrane insertion and even to perform functions after beingcleaved from the parent protein.Signal sequences have a well-characterized role in argeting and membraneinsertion. Different signal sequences guide their passenger proteins throughapparently common pathways and can be interchanged between different proteinsor even between proteins of different organisms. More specifically, signalsequences can discriminate between different targeting pathways, mediatetranslocation of the N-or the C-terminus across the membrane16, allow variablemembrane translocation such that the protein either remains in the cytoplasm, isinserted into the membrane or is translocated into the lumen17,18 or can evenhave a further function after cleavage from the parent protein.The characteristic feature of signal sequences is a hydropHobic core (h-)region comprising, for cleavable signal sequences, six to fifteen amino acidresidues. Analysis of signal sequence mutants showed that this h-region is themost essential part required for targeting and membrane insertion. The h-region isflanked on its C-terminal side by a polar (c-) region, which often containshelixbreaking proline and glycine residues as well as small uncharged residues inpositions –3 and –1 that determine the site of signal peptide cleavage. On itsN-terminal side, the h-region is flanked by a rather polar n-region, which usuallyhas a net positive charge. Comparative analysis of a large number of signalsequences reveals substantial variability in their overall length, ranging from 15 tomore than 50 amino acid residues. The n-region contributes most to the variationin overall length.