What is SLC2A1 gene?
The SLC2A1 gene provides instructions for producing a protein called the glucose transporter protein type 1 (GLUT1). The GLUT1 protein is embedded in the outer membrane surrounding cells, where it transports a simple sugar called glucose into cells from the blood or from other cells for use as fuel.
What is GLUT1 deficiency?
Glucose transporter type 1 deficiency syndrome (Glut1DS) is a rare genetic metabolic disorder characterized by deficiency of a protein that is required for glucose (a simple sugar) to cross the blood-brain barrier and other tissue barriers.
How many people have GLUT1?
Frequency. GLUT1 deficiency syndrome is a rare disorder. Approximately 500 cases have been reported worldwide since the disorder was first identified in 1991. In Australia, the prevalence of the disorder has been estimated at 1 in 90,000 people.
How many types of GLUT are there?
Fourteen GLUT proteins are expressed in the human and they are categorized into 3 classes based on sequence similarity.
How is GLUT1 deficiency diagnosed?
When GLUT1 deficiency is suspected, glucose is measured in the spinal fluid and in the blood. The first step is blood samples, followed by a spinal tap. Even if a spinal tap is the first test, genetic testing will help confirm the diagnosis. The genetic test usually detects a pathogenic variant in the SLC2A1 gene.
What is the difference between GLUT1 and GLUT4?
GLUT1 is expressed in most cells, is localized primarily at the cell membrane, and is thought to participate mainly in basal glucose transport in muscle. GLUT4 is expressed only by cells that accelerate glucose transport in response to insulin (skeletal muscle, heart muscle, and adipose cells).
Does GLUT1 require insulin?
GLUT1 is insulin-independent and is widely distributed in different tissues. GLUT4 is insulin-dependent and is responsible for the majority of glucose transport into muscle and adipose cells in anabolic conditions.
Is GLUT1 deficiency fatal?
Homozygous GLUT1 mutations presumably are lethal. The ketogenic diet is the treatment of choice as it provides an alternative fuel to the brain. It should be introduced early and maintained into puberty. Seizures are effectively controlled with the onset of ketosis, but might recur and require comedication.
What is GLUT1 GLUT2 GLUT3 and GLUT4?
Class I facilitative glucose transporters
Class I facilitative glucose transportors are represented by GLUT1 to GLUT4, among which GLUT2 is expressed mainly in beta cells of the pancreas, liver and kidney. GLUT2 acts as a glucose sensor in beta cells of marine organisms, but human beta cells express mainly GLUT1.
What is the difference between GLUT2 and GLUT4?
GLUT1 is the major glucose transporter in brain, placenta and erythrocytes, GLUT2 is found in the pancreas, liver and kidneys, GLUT3 is neuronal and placental, while GLUT4 is the insulin-responsive transporter found in skeletal muscle, heart and adipose tissue.
Is GLUT1 insulin dependent?
Where is GLUT1 found?
mammalian erythrocyte membrane
GLUT1 is highly abundant in the mammalian erythrocyte membrane where it can rapidly equilibrate glucose between the cytoplasm of the erythrocyte and the blood plasma. GLUT1 is also found in brain tissues. GLUT1 can also transport mannose, galactose, and glucosamine.
Where are GLUT3 transporters found?
GLUT3 is the most prominent glucose transporter isoform expressed in adult brain, where it tends to be preferentially located in neurones, rather than in other cell types, such as glia or endothelial cells. It is also widely distributed in other human tissues, having been detected in the liver, kidney and placenta.
Does GLUT1 use ATP?
ATP modulation of GLUT1-mediated transport is competitively inhibited by AMP and ADP, but does not require ATP hydrolysis (Heard et al., 2000).
Is GLUT1 insulin-dependent?
Is GLUT2 insulin-dependent?
It is the principal transporter for transfer of glucose between liver and blood Unlike GLUT4, it does not rely on insulin for facilitated diffusion.
Is GLUT4 insulin-dependent?
GLUT4 is an insulin-regulated glucose transporter that is responsible for insulin-regulated glucose uptake into fat and muscle cells. In the absence of insulin, GLUT4 is mainly found in intracellular vesicles referred to as GLUT4 storage vesicles (GSVs).
Is GLUT1 responsive to insulin?
Why is GLUT1 Important?
GLUT1 is responsible for the low level of basal glucose uptake required to sustain respiration in all cells. Expression levels of GLUT1 in cell membranes are increased by reduced glucose levels and decreased by increased glucose levels.
What is the difference between GLUT1 and GLUT3?
GLUT1 is primarily responsible for transport of glucose across the blood-brain barrier, and GLUT3 controls the uptake of glucose into the neuron.
What is the function of GLUT3?
GLUT3 is responsible for transporting glucose from extracellular space to neuronal tissue, specifically dendrites and axons. Decreased levels of GLUT3 in Alzheimer brain shows a positive correlation to decreased levels of N-acetylglucosamine, which is a derivative of glucose.
Why is GLUT4 insulin-dependent?
GLUT4 functions for the insulin-dependent translocation of glucose. Thus, insulin stimulates the uptake of glucose by GLUT4 in the muscle cell where hexokinase converts it to glucose-6-phosphate so that the cell may utilize it for either glycolysis for energy or for the formation of glycogen when glucose is abundant.
What happens to GLUT4 without insulin?
In the absence of insulin, Glut4 slowly recycles between the plasma membrane and vesicular compartments within the cell, where most of the Glut4 resides.
What activates GLUT4?
The GLUT4 carrier vesicles are either transferrin positive or negative, and are recruited by different stimuli. Transferrin-positive GLUT4 vesicles are utilized during muscle contraction while the transferrin-negative vesicles are activated by insulin stimulation as well as by exercise.
What type of transporter is GLUT1?
uniporter protein
Glucose transporter 1 (or GLUT1), also known as solute carrier family 2, facilitated glucose transporter member 1 (SLC2A1), is a uniporter protein that in humans is encoded by the SLC2A1 gene. GLUT1 facilitates the transport of glucose across the plasma membranes of mammalian cells.