PMID- 10601238
OWN - NLM
STAT- MEDLINE
DCOM- 20000113
LR  - 20190508
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 274
IP  - 52
DP  - 1999 Dec 24
TI  - Identification and functional characterization of a novel, tissue-specific
      NAD(+)-dependent isocitrate dehydrogenase beta subunit isoform.
PG  - 36866-75
AB  - To understand the interactions and functional role of each of the three
      mitochondrial NAD(+)-dependent isocitrate dehydrogenase (IDH) subunits (alpha,
      beta, and gamma), we have characterized human cDNAs encoding two beta isoforms
      (beta(1) and beta(2)) and the gamma subunit. Analysis of deduced amino acid
      sequences revealed that beta(1) and beta(2) encode 349 and 354 amino acids,
      respectively, and the two isoforms only differ in the most carboxyl 28 amino
      acids. The gamma cDNA encodes 354 amino acids and is almost identical to monkey
      IDHgamma. Northern analyses revealed that the smaller beta(2) transcript (1.3
      kilobases) is primarily expressed in heart and skeletal muscle, whereas the
      larger beta(1) mRNA (1.6 kilobases) is prevalent in nonmuscle tissues. Sequence
      analysis of the IDHbeta gene indicates that the difference in the C-terminal 28
      amino acids between beta(1) and beta(2) proteins results from alternative
      splicing of a single transcript. Among the various combinations of human IDH
      subunits co-expressed in bacteria, alphabetagamma, alphabeta, and alphagamma
      combinations exhibited significant amounts of IDH activity, whereas subunits
      produced alone and betagamma showed no detectable activity. These data suggest
      that the alpha is the catalytic subunit and that at least one of the other two
      subunits plays an essential supporting role for activity. Substitution of beta(1)
      with beta(2) in the co-expression system lowered the pH optimum for IDH activity 
      from 8.0 to 7.6. This difference in optimal pH was analogous to what was observed
      in mouse kidney and brain (beta(1) prevalent; optimal pH 8.0) versus heart
      (beta(2) prevalent; pH 7.6) mitochondria. Experiments with a specially designed
      splicing reporter construct stably transfected into HT1080 cells indicate that
      acidic conditions favor a splicing pattern responsible for the muscle- and
      heart-specific beta(2) isoform. Taken together, these data indicate a regulatory 
      role of IDHbeta isoforms in determining the pH optimum for IDH activity through
      the tissue-specific alternative splicing.
FAU - Kim, Y O
AU  - Kim YO
AD  - Department of Genetic Engineering, College of Natural Sciences, Kyungpook
      National University, Taegu 702-701, Korea.
FAU - Koh, H J
AU  - Koh HJ
FAU - Kim, S H
AU  - Kim SH
FAU - Jo, S H
AU  - Jo SH
FAU - Huh, J W
AU  - Huh JW
FAU - Jeong, K S
AU  - Jeong KS
FAU - Lee, I J
AU  - Lee IJ
FAU - Song, B J
AU  - Song BJ
FAU - Huh, T L
AU  - Huh TL
LA  - eng
SI  - GENBANK/AF023265
SI  - GENBANK/AF046929
SI  - GENBANK/U40272
SI  - GENBANK/U49283
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (DNA, Complementary)
RN  - 0 (Isoenzymes)
RN  - 0 (RNA, Messenger)
RN  - EC 1.1.1.41 (Isocitrate Dehydrogenase)
SB  - IM
MH  - Alternative Splicing
MH  - Amino Acid Sequence
MH  - Animals
MH  - Base Sequence
MH  - Cattle
MH  - Cells, Cultured
MH  - Cloning, Molecular
MH  - DNA, Complementary/biosynthesis/isolation & purification
MH  - Humans
MH  - Hydrogen-Ion Concentration
MH  - Isocitrate Dehydrogenase/chemistry/*genetics/physiology
MH  - Isoenzymes/chemistry/*genetics/physiology
MH  - Mice
MH  - Molecular Sequence Data
MH  - Organ Specificity
MH  - RNA, Messenger/analysis
EDAT- 1999/12/22 00:00
MHDA- 1999/12/22 00:01
CRDT- 1999/12/22 00:00
PHST- 1999/12/22 00:00 [pubmed]
PHST- 1999/12/22 00:01 [medline]
PHST- 1999/12/22 00:00 [entrez]
AID - 10.1074/jbc.274.52.36866 [doi]
PST - ppublish
SO  - J Biol Chem. 1999 Dec 24;274(52):36866-75. doi: 10.1074/jbc.274.52.36866.