Catalysis of the transfer of choline from one side of the membrane to the other. Choline (2-hydroxyethyltrimethylammonium) is an amino alcohol that occurs widely in living organisms as a constituent of certain types of phospholipids and in the neurotransmitter acetylcholine.
Enables the directed movement of creatine across a membrane. Creatine is a compound synthesized from the amino acids arginine, glycine, and methionine that occurs in muscle.
Creatine and creatine phosphate act as a buffer system for the regeneration of ATP in tissues with fluctuating energy demands. Following reports of the cloning of a creatine transporter in rat, rabbit, and human, we cloned and sequenced a creatine transporter from a human intestinal cDNA library. PCR amplification of genomic DNAs from somatic cell hybrid panels localized two creatine transporter (CT) genes: CT1 to Xq26-q28 and CT2 to 16p11.2. Refinement of CT1 to Xq28 was confirmed by FISH. Identification of CT2 sequences in YACs and cosmid contigs that had been ordered on human chromosome 16 enabled its assignment to the proximal end of 16p11.2. Sequencing of the CT2 gene identified sequence differences between CT1 and CT2 transcripts that were utilized to determine that CT2 is expressed in testis only. CT2 is the most proximally identified gene on chromosome 16p to date. The existence of an autosomal, testis-specific form of the human creatine transporter gene suggests that creatine transporter activity is critical for normal function of spermatazoa following meiosis.
Catalysis of the transfer of a solute or solutes from one side of a membrane to the other according to the reaction: creatine(out) + Na+(out) = creatine(in) + Na+(in).
Catalysis of the transfer of a solute or solutes from one side of a membrane to the other according to the reaction: neurotransmitter(out) + Na+(out) = neurotransmitter(in) + Na+(in).
The directed movement of creatine into, out of or within a cell, or between cells, by means of some agent such as a transporter or pore. Creatine is a compound synthesized from the amino acids arginine, glycine, and methionine that occurs in muscle.
Creatine and creatine phosphate act as a buffer system for the regeneration of ATP in tissues with fluctuating energy demands. Following reports of the cloning of a creatine transporter in rat, rabbit, and human, we cloned and sequenced a creatine transporter from a human intestinal cDNA library. PCR amplification of genomic DNAs from somatic cell hybrid panels localized two creatine transporter (CT) genes: CT1 to Xq26-q28 and CT2 to 16p11.2. Refinement of CT1 to Xq28 was confirmed by FISH. Identification of CT2 sequences in YACs and cosmid contigs that had been ordered on human chromosome 16 enabled its assignment to the proximal end of 16p11.2. Sequencing of the CT2 gene identified sequence differences between CT1 and CT2 transcripts that were utilized to determine that CT2 is expressed in testis only. CT2 is the most proximally identified gene on chromosome 16p to date. The existence of an autosomal, testis-specific form of the human creatine transporter gene suggests that creatine transporter activity is critical for normal function of spermatazoa following meiosis.
A process in which force is generated within muscle tissue, resulting in a change in muscle geometry. Force generation involves a chemo-mechanical energy conversion step that is carried out by the actin/myosin complex activity, which generates force through ATP hydrolysis.
During the course of a large-scale sequencing project in Xq28, a human creatine transporter (CRTR) gene was discovered. The gene is located approximately 36 kb centromeric to ALD. The gene contains 13 exons and spans about 8.5 kb of genomic DNA. Since the creatine transporter has a prominent function in muscular physiology, it is a candidate gene for Barth syndrome and infantile cardiomyopathy mapped to Xq28.
The directed movement of substances (such as macromolecules, small molecules, ions) into, out of or within a cell, or between cells, or within a multicellular organism by means of some agent such as a transporter or pore.
The complete coding sequence from a human creatine transporter cDNA was isolated from a kidney library. This transporter is a member of a superfamily of proteins which includes the family of Na(+)- and Cl(-)-dependent transporters responsible for the uptake of certain neurotransmitters (e.g. dopamine, GABA, serotonin, and norepinephrine), and amino acids (e.g. glycine). Within this family, the human creatine transporter is strongly related to a subfamily of sequences which includes the transporters for taurine, GABA, and betaine, and this cDNA is approximately 98% amino acid identical to sequences that have been reported from rat and rabbit as choline and creatine transporters respectively. Pharmacological characterization demonstrated that the protein product of this cDNA mediated high affinity (Km = 77 +/- 6 microM) creatine uptake, which was blocked by creatine analogs with high affinity. There was no specific transport of choline. Northern analysis demonstrated highest levels of mRNA expression in human skeletal muscle, kidney, and heart, with lower levels in brain and other tissues. Expression within the kidney was evenly distributed between cortex and medulla. Genetic mapping in the mouse localizes the creatine transporter to a region on the X chromosome in linkage conservation with the human region Xq28, the location of the genes for several neuromuscular diseases.
Protein involved in the transport of ions. Such proteins are usually transmembrane and mediate a movement of ions across cell membranes. Transport may be passive (facilitated diffusion; down the electrochemical gradient), or active (against the electrochemical gradient). Active transport requires energy which may come from light, oxidation reactions, ATP hydrolysis, or cotransport of other ions or molecules.
Protein involved in the movement of sodium ions across energy- transducing cell membranes. Primary active sodium transport is coupled to an energy-yielding chemical reaction such as ATP hydrolysis. Secondary active transport utilizes the voltage and ion gradients produced by the primary transport to drive the cotransport of other ions or molecules. These may be transported in the same (symport) or opposite (antiport) direction.
Protein involved in the transport of solutes across a biological membrane in one direction, which depends on the transport of another solute in the same direction. One molecule can move up an electrochemical gradient because the movement of the other molecule is more favorable. Example: the sodium/glucose co-transport.
Protein involved in the transport of a molecule (metabolite, protein, etc), a ion or an electron across cell membranes, inside the cell or in a tissue fluid.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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