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Facilitated diffusion is the process of spontaneous passive transport of molecules or ions across a biological membrane via specific transmembrane integral proteins. Being passive, facilitated transport does not directly require chemical energy from ATP hydrolysis in the transport step itself; rather, molecules and ions move down their concentration gradient reflecting its diffusive nature.
β-Galactosidase, is a glycoside hydrolase enzyme that catalyzes hydrolysis of terminal non-reducing β-D-galactose residues in β-D-galactosides.
The lactose operon is an operon required for the transport and metabolism of lactose in E. coli and many other enteric bacteria. Although glucose is the preferred carbon source for most bacteria, the lac operon allows for the effective digestion of lactose when glucose is not available through the activity of beta-galactosidase. Gene regulation of the lac operon was the first genetic regulatory mechanism to be understood clearly, so it has become a foremost example of prokaryotic gene regulation. It is often discussed in introductory molecular and cellular biology classes for this reason. This lactose metabolism system was used by François Jacob and Jacques Monod to determine how a biological cell knows which enzyme to synthesize. Their work on the lac operon won them the Nobel Prize in Physiology in 1965.
PEP group translocation, also known as the phosphotransferase system or PTS, is a distinct method used by bacteria for sugar uptake where the source of energy is from phosphoenolpyruvate (PEP). It is known to be a multicomponent system that always involves enzymes of the plasma membrane and those in the cytoplasm.
Isopropyl β-d-1-thiogalactopyranoside (IPTG) is a molecular biology reagent. This compound is a molecular mimic of allolactose, a lactose metabolite that triggers transcription of the lac operon, and it is therefore used to induce protein expression where the gene is under the control of the lac operator.
Galactoside permease is a protein coded by the lacY gene of the lac operon, and is found bound to the membrane of a cell for the purpose of binding galactoside molecules that have been solubilized. The protein is part of a system whose main function is to catalyze the accumulation and transport of lactose and other beta-galactosides across the permeable barrier of a membrane.
Phosphatidylethanolamine (PE) is a class of phospholipids found in biological membranes. They are synthesized by the addition of cytidine diphosphate-ethanolamine to diglycerides, releasing cytidine monophosphate. S-Adenosyl methionine can subsequently methylate the amine of phosphatidylethanolamines to yield phosphatidylcholines.
In enzymology, an oligopeptide-transporting ATPase (EC 3.6.3.23) is an enzyme that catalyzes the chemical reaction
In enzymology, an oligosaccharide-transporting ATPase (EC 3.6.3.18) is an enzyme that catalyzes the chemical reaction
In enzymology, a protein-Npi-phosphohistidine-sugar phosphotransferase is an enzyme that catalyzes the chemical reaction
Carbon catabolite repression, or simply catabolite repression, is an important part of global control system of various bacteria and other microorganisms. Catabolite repression allows microorganisms to adapt quickly to a preferred carbon and energy source first. This is usually achieved through inhibition of synthesis of enzymes involved in catabolism of carbon sources other than the preferred one. The catabolite repression was first shown to be initiated by glucose and therefore sometimes referred to as the glucose effect. However, the term "glucose effect" is actually a misnomer since other carbon sources are known to induce catabolite repression.
Lactose permease is a membrane protein which is a member of the major facilitator superfamily. Lactose permease can be classified as a symporter, which uses the proton gradient towards the cell to transport β-galactosides such as lactose in the same direction into the cell.
Howard Ronald Kaback was an American biochemist, known for Kabackosomes, the cell-free membrane transport vesicles. He was the brother of Michael M. Kaback, pediatrician and human geneticist, who developed a screening program to detect and prevent Tay–Sachs disease, a rare and fatal genetic disorder most common in Ashkenazi Jews.
The Hydroxy/Aromatic Amino Acid Permease (HAAAP) Family is a member of the large Amino Acid-Polyamine-OrganoCation (APC) Superfamily of secondary carrier proteins. Members of the HAAAP family all function in amino acid uptake. Homologues are present in a large number of Gram-negative and Gram-positive bacteria, with at least one member classified from archaea .
The lactate permease (LctP) family is a family of transport proteins belonging to the ion transporter (IT) superfamily.
The Pho1 phosphate permease family is a family of phosphate transporters belonging to the ion transporter (IT) superfamily. Representative members of the Pho1 family include the putative phosphate transporter PHO1 of Arabidopsis thaliana, and the xenotropic and polytropic murine-leukemia virus receptor Xpr1 of Culex pipiens.
The inorganic phosphate transporter (PiT) family is a group of carrier proteins derived from Gram-negative and Gram-positive bacteria, archaea, and eukaryotes.
The phosphotransferases system (PTS-GFL) superfamily is a superfamily of phosphotransferase enzymes that facilitate the transport of glucose, glucitol (G), fructose (F) and lactose (L). Classification has been established through phylogenic analysis and bioinformatics.
The PTS Lactose-N,N’-Diacetylchitobiose (Lac) Family includes several sequenced lactose porters of Gram-positive bacteria, as well as the Escherichia coli and Borrelia burgdorferi N,N'-diacetylchitobiose (Chb) porters. It is part of the PTS-GFL superfamily. The former can transport aromatic β-glucosides and cellobiose, as well as Chb. However, only Chb induces expression of the chb operon.
The Glycoside-Pentoside-Hexuronide (GPH):Cation Symporter Family is part of the major facilitator superfamily and catalyzes uptake of sugars (mostly, but not exclusively, glycosides) in symport with a monovalent cation (H+ or Na+). The various members of the family have been reported to use Na+, H+ or Li, Na+ or Li+, or all three cations as the symported cation.
References
- ↑ "Substrate Transport in Lactose Permease".
- ↑ J., Ninfa, Alexander; P., Ballou, David (2004). Fundamental laboratory approaches for biochemistry and biotechnology. Wiley. ISBN 1891786008. OCLC 633862582.
