Lmost unaltered. Subsequent, we turned to two newly found proteins that
Lmost unaltered. Next, we turned to two newly found proteins that do not have an clear function in lipid metabolism. The protein encoded by the DDB0184006 gene did not bear significant homologies to any gene from other organisms. We produced N-terminal also as C-terminal fusions of GFP for the coding area, and both hybrids changed their distribution from the ER (Fig. 4A and C) to lipid droplets upon fatty acid addition (Fig. 4B and D). As a result, we named the protein Ldp (for lipid droplet protein). The gene is named ldpA in accordance with Dictyostelium nomenclature guidelines. The amino acid sequence of this protein is very rich in asparagine and lysine residues, resulting in an all round isoelectric point of 9.5, in accordance with many calculation strategies. By far the most acidic patch (pI four.1) involving residues 305 to 356 probably participates inside the formation of a coiled-coil structure (Fig. 4E, red residues). In addition, Ldp is characterized by a higher content material of serine and threonine residues, opening the possibility of being phosphorylated; on the other hand, we didn’t detect obvious shifts in molecular masses on Western blots from samples derived from distinctive cultivation situations. These predominant amino acids generally occur in homooligomeric repeats of as much as 9 residues. World wide web resources also predict the presence of three transmembrane domains (Fig. 4E, blue residues). To verify the validity of this prediction, we attempted to extract Ldp-GFP with numerous buffers from the endoplasmic reticulum membrane and succeeded only when the detergent Triton X-100 was applied (Fig. 4F). The Ldp hybrid with GFP fused to the N terminus behaved in the similar way. Homologs of your third protein, encoded by the DDB0238661 gene, are identified in plants, insects, and vertebrates with identities ranging amongst 25 and 30 only. A rather low value of conservation is also identified in other Dictyostelium species like Dictyostelium purpureum and Dictyostelium fasciculatum, which bear just 56 and 38 identical residues, respectively. The corresponding protein is ideal studied in mammals, where it truly is named DUF829 (for domains of unknown function), Tmem53 (for transmembrane protein) or, most regularly, NET4 (for nuclear envelope transmembrane protein 4). The name adopted for Dictyostelium protein is Net4, encoded by the netD locus. Certainly, this name seems appropriate because both GFP fusions localize towards the endoplasmic reticulum in Dictyostelium cells, with an apparent enrichment in the nuclear envelope (Fig. 5A, B, and C) as in mammals (43). When Net4-GFP-expressing cells are stimulated with fatty acids, the protein moves to lipid droplets, as well as the staining of endoplasmic reticulum and nuclear envelope is concomitantly decreased (Fig. 5D). The GFP-Net4 fusion, nonetheless, fails to undergo this redistribution (Fig. 5B). To test no matter if the mammalian NET4 protein also redistributes to lipid droplets under appropri-November 2013 Volume 12 Numberec.asm.orgDu et al.TABLE 1 Protein constituents of lipid dropletsMASCOT score by conditionb 1st 930 2nd 968 3rd 2,348 Mean MASCOT scorec 1,416 Presence in LDs of other cell sort(s)d B, C, DProtein group and identification no.a Structural LD protein DDB0235170 Enzymes of lipid metabolism DDB0237965 DDB0191105 JNK1 Formulation DDB0304900 DDB0185188 DDB0304901 DDB0238829 DDB0238830 IL-17 Purity & Documentation DDB0219382 DDB0233097 DDB0205694 DDB0233059 DDB0235400 DDB0230057 DDB0190742 DDB0232044 Modest GTPases DDB0191507 DDB0214821 DDB0191476 DDB0201663 DDB0191190 DDB0201639 DDB0229398 DD.