Biomaterial Database

Mitochondrial carrier proteins can reversibly change their transport mode: the cases of the aspartate/glutamate and the phosphate carrier. 1998

R Krämer

Institute of Biotechnology 1, Forschungszentrum Juelich GmbH, Germany. r.kraemer@rsl.rrz.uni-koeln.de

A number of mitochondrial carrier systems function both in homologous and in heterologous exchange mode, which, in the case of the phosphate carrier is a homologous Pi(-)-Pi- and a heterologous Pi(-)-OH- exchange. In addition, we showed that mitochondrial carriers, e.g. the aspartate/glutamate and the phosphate carrier, can undergo a functional shift from coupled antiport to uncoupled uniport after modification of cysteine residues. In this transport mode a mixture of carrier- and channel-type properties is observed. To address this question on the molecular level, the phosphate carrier from yeast (S. cerevisiae) mitochondria was expressed in E. coli, solubilized, purified and functionally reconstituted. From three cysteine residues present in the yeast phosphate carrier at positions 28, 134 and 300, only one single cysteine residue (C28) was found responsible for the functional switch from antiport to uniport. Upon replacement by a serine residue, this interconversion was blocked. After incorporation of the carrier into giant liposomes, electrophysiological methods (patch clamp) were applied. Under these conditions, a fourth transport mode of the phosphate carrier was observed, namely an action as anion-selective channel, which could be reversibly blocked by phosphate.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008928	Mitochondria	Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic
D017433	Protein Structure, Secondary	The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to ALPHA-HELICES; BETA-STRANDS (which align to form BETA-SHEETS), or other types of coils. This is the first folding level of protein conformation.	Secondary Protein Structure,Protein Structures, Secondary,Secondary Protein Structures,Structure, Secondary Protein,Structures, Secondary Protein
D017920	Antiporters	Membrane transporters that co-transport two or more dissimilar molecules in the opposite direction across a membrane. Usually the transport of one ion or molecule is against its electrochemical gradient and is "powered" by the movement of another ion or molecule with its electrochemical gradient.	Anion Exchange Proteins,Antiporter,Cation Exchange Proteins,Anion Exchangers (Proteins),Cation Exchangers (Proteins),Exchange Proteins, Anion,Exchange Proteins, Cation
D026922	Amino Acid Transport Systems, Acidic	Amino acid transporter systems capable of transporting acidic amino acids (AMINO ACIDS, ACIDIC).	Acidic Amino Acid Transport Systems,Amino Acid Transport Systems, Anionic,Anionic Amino Acid Transport Systems,Acidic Amino Acid Transport Proteins,Acidic Amino Acid Transporters,Anionic Amino Acid Transport Proteins,Anionic Amino Acid Transporters