Isoforms of fatty‐acid‐binding protein in bovine heart are coded by distinct mRNA

Abstract

In the course of our studies on structure/function relationships of fatty‐acid‐binding proteins, we reported earlier that the two isoforms of the 15‐kDa cardiac fatty‐acid‐binding protein (cFABP) from bovine heart only differ in one position; Asn98 in pl 5.1‐cFABP; Asp98 in pI 4.9‐cFABP [Unterberg, C., Börchers, T., Højrup, P., Knudsen, J. and Spener, F. (1990) J. Biol. Chem. 265, 16 255–16 261]. In the present study, we elucidate the origin for this heterogeneity. Isoelectric focusing analysis of immunoprecipitated in vitro translation products from total mRNA and positivehybrid‐selected cFABP/mRNA revealed two l‐[35S]methionine‐labeled proteins corresponding to pI 5.1‐cFABP and pI 4.9‐cFABP. In a control experiment, recombinant mRNA derived from cDNA encoding pI 5.1‐cFABP was translated and produced only pI 5.1‐cFABP as shown by isoelectric focusing of the translation products. We could observe co‐translational acetylation but not posttranslational deamidation of the cFABP isoforms. Taken together, our results demonstrate that the isoforms of cardiac fatty‐acid‐binding protein found in bovine heart are coded by distinct mRNA species.

Cloning and Tissue Expression of Chicken Heart Fatty Acid-Binding Protein and Intestine Fatty Acid-Binding Protein Genes

“…4). The tissue distribution of H-FABP and I-FABP mRNA were similar to that previously reported in rat or human (3,15,16). …”

Mammary Derived Growth Inhibitor Is Not a Distinct Protein but a Mix of Heart-type and Adipocyte-type Fatty Acid-binding Protein

“…1, lane 2). We presented arguments (31) that the isoforms stem from two different mRNAs rather than from posttranslational modification (deamidation).…”

“…Isoelectric focusing was performed under denaturing conditions as described earlier (31). Two-dimensional gel electrophoresis, which was also performed under denaturing conditions, and Western blotting were done as described by Nielsen and Spener (30).…”

New insights into the structure and function of fatty acid-binding proteins

“…Two isoforms of bovine H-FABP were reported, with Asp or Asn at position 98 [60]. The heterogeneity was caused by distinct mRNA species [61], but whether this is due to different genes, alternative splicing or RNA editing is not yet clear. Phelan et al [31] reported a Lys53Arg substitution in human H-FABP which had a low frequency in a Swedish population and showed no association with breast cancer incidence.…”