Human lipoprotein lipase last exon is not translated, in contrast to lower vertebrates

Abstract

We have sequenced the first fish (zebrafish, Brachydanio rerio) lipoprotein lipase (LPL) cDNA clone. Similarities were found in mammalian LPL cDNA, but the codon spanning the last two exons (which is thus split by the last intron) is AGA (Arg) as opposed to TGA in mammals. Exon 10 is thus partially translated. These results were confirmed with rainbow trout (Oncorhynchus mykiss). We also investigated whether mammal TGA coded for selenocystein (SeCys), the 21st amino acid, but found that this was not the case: TGA does not encode SeCys but is a stop codon. It thus appears that the sense codon AGA (fish) has been transformed into a stop codon TGA (human) during the course of evolution. It remains to be determined if the "loss" of the C-terminal end of mammalian LPL protein has conferred an advantage in terms of LPL activity or, on the contrary, a disadvantage (e.g., susceptibility to diabetes or atherosclerosis).

Two Isoforms of a Human Intersectin (ITSN) Protein Are Produced by Brain-Specific Alternative Splicing in a Stop Codon

“…1b and 1d). Termination codons split between two exons have been previously observed in other genes except that no alternative splicing has been described (Arnault et al, 1996;Koczan et al, 1991). Recent studies on the neural specificity of splicing indicate that the RNA regulatory regions that encompass "neuron-specific" exons and adjacent introns in general contain a complex arrangement of opposing signals that allow for positive and negative control mechanisms to operate in both neuronal and nonneuronal cells (Black, 1992;Min et al, 1997).…”

Zebrafish yolk lipid processing: a tractable tool for the study of vertebrate lipid transport and metabolism

“…S1D). In the circulatory system, LPL cleaves TAG from circulating lipoproteins, releasing fatty acids for cellular uptake and further metabolism (Arnault et al, 1996; Lindberg and Olivecrona, 2002; Wang et al, 2009). Supporting this, 4 hours after the injection, 3 H-palmitate was incorporated into additional phospholipids other than PC [phosphatidlyethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI) and sphingomyelin (SM)] (Fig.…”

A Novel Vertebrate Myoglobin Gene Containing Three A+T-Rich Introns Is Conserved Among Antarctic Teleost Species Which Differ in Myoglobin Expression

“…The small intron size of icefish Mb may be a general characteristic of teleosts. Several genes from varied species indicate that fish introns are severalfold shorter than their mammalian counterparts in homologous genes (Brenner et al 1993;Arnault et al 1996;Gauvry et al 1996). Introns average 80 bp among 10 pufferfish genes (Brenner et al 1993) and the three introns of the C. aceratus fatty acid binding protein (FABP) gene range from 80 to 603 bp (Hatch, Small, Sidell, and Vayda, unpublished results).…”