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G Bethlendy

Publications and source records attributed to G Bethlendy.

4 recordsLinked to original sources
PubMed1997

Association of HSP60-like proteins with the L-system amino acid transporter.

The carrier protein(s) responsible for mammalian L-system amino acid transport has not been identified. Chronic lymphocytic leukemia (CLL) B-lymphocytes have markedly diminished L-system transport which is restored after treatment with 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Six candidate L-system related plasma membrane proteins were identified in TPA-treated CLL-cells using an L-system photoprobe and ultra-high-resolution two-dimensional gel electrophoresis. In the current studies, two candidate L-system related proteins were obtained from preparative giant two dimensional gels, and the amino acid sequences of peptide fragments from these proteins were determined by Edman degradation. These proteins, forming a doublet on the gels at an apparent size of 40 kDa and pI 5.85, had sequence homology to the mitochondrial heat shock protein 60 (hsp60). The presence of these proteins in CLL lymphocyte plasma membranes was confirmed by immunoblotting with antibodies to hsp60. These observations indicate that an hsp60 homologue is associated with the L-system amino acid transporter.

Amino Acid Sequence↗
PubMed1993

CYC2 encodes a factor involved in mitochondrial import of yeast cytochrome c.

The gene CYC2 from the yeast Saccharomyces cerevisiae was previously shown to affect levels of mitochondrial cytochrome c by acting at a posttranslational step in cytochrome c biosynthesis. We report here the cloning and identification of the CYC2 gene product as a protein involved in import of cytochrome c into mitochondria. CYC2 encodes a 168-amino-acid open reading frame with at least two potential transmembrane segments. Antibodies against a synthetic peptide corresponding to the carboxyl terminus of the predicted sequence were raised. These antibodies recognize multiple bands on immunoblots of mitochondrial extracts. The intensities of these bands vary according to the gene dosage of CYC2 in various isogenic strains. Immunoblotting of subcellular fractions suggests that the CYC2 gene product is a mitochondrial protein. Deletion of CYC2 leads to accumulation of apocytochrome c in the cytoplasm. However, strains with deletions of this gene still import low levels of cytochrome c into mitochondria. The effects of cyc2 mutations are more pronounced in rho- strains than in rho+ strains, even though rho- strains that are CYC2+ contain normal levels of holocytochrome c. cyc2 mutations affect levels of iso-1-cytochrome c more than they do levels of iso-2-cytochrome c, apparently because of the greater susceptibility of apo-iso-1-cytochrome c to degradation in the cytoplasm. We propose that CYC2 encodes a factor that increases the efficiency of cytochrome c import into mitochondria.

Amino Acid Sequence↗
PubMedDate not supplied

Prohibitin expression is increased in phorbol ester-treated chronic leukemic B-lymphocytes.

Chronic lymphocytic leukemia (CLL) is characterized by the gradual accumulation of immature B-lymphocytes. CLL B-lymphocytes mature to a plasmacytoid phenotype when treated in vitro with phorbol esters. CLL B-cell apparent maturation is associated with altered expression of specific plasma membrane and mitochondrial proteins including heightened expression of a 30-kDa heat shock protein 60 (hsp60) analog. During our efforts to further characterize this hsp60 analog by mass spectrometry, we detected the mitochondrial protein prohibitin in phorbol-ester-matured CLL B-lymphocytes. Prohibitin modulates cell proliferation and inhibits cell cycle traverse in several systems, although few data are available for lymphocytes. A twofold increase in prohibitin concentration was observed in phorbol-ester-matured compared to resting CLL B-cells as determined by quantitative Western immunoblot analysis. A similar increase in prohibitin was observed in phorbol-ester-treated normal human B-lymphocyte populations. An antisense oligonucleotide complementary to the 5' coding region of the prohibitin gene blunted the increase in prohibitin protein in phorbol-ester-treated CLL B-cells by 42%. These data suggest that increased prohibitin expression is associated with and may facilitate B-cell maturation.

Antineoplastic Agents↗