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Isolation and identification of a mouse brain protein recognized by antisera to heart fatty acid‐binding protein
Author(s) -
Pu Lixia,
Annan Roland S.,
Carr Steven A.,
Frolov Andrey,
Wood W. Gibson,
Spener Friedrich,
Schroeder Friedhelm
Publication year - 1999
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-999-0374-8
Subject(s) - fatty acid binding protein , heart type fatty acid binding protein , biochemistry , gene isoform , amino acid , isoelectric point , isoelectric focusing , fatty acid , peptide sequence , biology , peptide mass fingerprinting , methionine , peptide , binding protein , protein isoform , chemistry , microbiology and biotechnology , proteomics , enzyme , alternative splicing , gene
Although a novel brain‐specific fatty acid‐binding protein (B‐FABP) was recently cloned, the identity of a second fatty acid‐binding protein detected with antibodies to the heart (H‐FABP) has not been clearly resolved. The present investigation, using matrix‐assisted laser desorption mass spectrometry, showed that this protein was a form of H‐FABP whose N‐terminal amino acid was neither methionine nor was it acetylated. Furthermore, isoelectric focusing revealed two major isoforms, a major band pl 7.4 and a minor band pl 6.4, in a distribution pattern opposite to that observed for H‐FABP in the heart. Tryptic peptide mass maps of the in‐gel digested SDS polyacrylamide gel electrophoresis protein bands showed that the two isoforms differed only in a single peptide corresponding to residues 97–106 of the heart H‐FABP sequence. This peptide had an [M+H] + ion of either 1205.62 (pl 7.4) or 1206.53 (pl 6.4), consistent with a single amino acid substitution, Asp98 or Asn98. Whereas it is well established that both H‐FABP and B‐FABP interact with polyunsaturated fatty acids, we showed that they also significantly alter plasma membrane cholesterol dynamics in a manner opposite to that of another brain lipidbinding protein, sterol carrier protein‐2. In summary, the data demonstrated for the first time that the H‐FABP from brain, while nearly identical to H‐FABP from heart, differed significantly in isoform distribution and in amino terminal structure from heart H‐FABP. This suggests that the brain and heart H‐FABP may not necessarily function identically in these tissues.