Cloning of a full-length complementary DNA for fatty-acid-binding protein from bovine heart (original) (raw)

1988, European Journal of Biochemistry

A full-length cDNA for bovine heart fatty-acid-binding protein (H-FABP) was cloned from a Igtl 1 cDNA library established from bovine heart muscle. The cDNA sequence shows an open reading frame coding for a protein with 133 amino acids. Colinearity with the amino acid sequences of four tryptic peptides was asserted. H-FABP isolated from bovine heart begins with an N-acetylated valine residue, however, as derived from analysis of the tryptic, amino-terminal-blocked peptide and the molecular mass of the peptide obtained via secondary-ion mass spectrometry. The molecular mass of the total protein is 14673 Da. Bovine H-FABP is 89% homologous to rat H-FABP and 97% homologous to the bovine mammary-derived growth-inhibition factor described recently by Bohmer et al. [J. Biol. Chem. 262, 15137-15143 (1987)l. Significant homologies were also found with bovine myelin protein P2 and murine adipocyte protein p422. Secondary-structure predictions were proposed for these proteins, based on computer analysis, which reveal striking similarities. Non-enzymatic 14-15-kDa proteins that bind fatty acids and fatty-acyl-CoA esters are abundant in the cytosol of cardiac tissues of mammals [2] including man 131. These 'cardiactype fatty-acid-binding proteins' (H-FABP), together with the fatty-acid-binding proteins of the hepatic (L-FABP) and intestinal (I-FABP) type, form, by the criteria of molecular mass and ligand binding, a group of related, yet structurally distinct proteins, whose functions are not well understood at present [2, 41. Presumed roles include (a) promoting the cellular uptake and intracellular utilization of fatty acids, (b) targetting fatty acids and acyl-CoAs to organelles, (c) modulating enzyme activities of lipid metabolism and (d) solubilizing fatty acids and acyl-CoAs in aqueous compartments. With oxidative fatty acid metabolism prevalent in heart cells, H-FABP has been inferred to take part in the delivery of fatty acids to mitochondria by a mechanism where a reversible self-aggregation of H-FABP in competition with its binding of fatty acids regulates the availability of fatty acids for /?-oxidation [5]. Glatz et al. observed a diurnal variation of H-FABP contents in rat heart cells, from 4% of cytosolic proteins at noon to 8% at midnight, that correlated with palmitate oxidation [6]. After immunoassays and cDNA probes for ratfatty-acid-binding proteins became available, it was shown