What is the role of the GLUT4 in response to insulin?
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).
How does insulin recruit GLUT4?
Under conditions of low insulin, most GLUT4 is sequestered in intracellular vesicles in muscle and fat cells. As the vesicles fuse with the plasma membrane, GLUT4 transporters are inserted and become available for transporting glucose, and glucose absorption increases.
What is GLUT4 stimulated by?
Insulin stimulates glucose transport in fat and skeletal muscle cells primarily by inducing the translocation of GLUT4 (glucose transporter isoform 4) to the PM (plasma membrane) from specialized GSVs (GLUT4 storage vesicles).
What signaling pathway does insulin use?
The two main pathways of insulin signaling emanating from the insulin receptor-IRS node are the phosphatidylinositol 3-kinase (PI3K, a lipid kinase)/AKT (also known as PKB or protein kinase B) pathway (86,87) and the Raf/Ras/MEK/ MAPK (mitogen activated protein kinase, also known as ERK or extracellular signal …
Does insulin stimulated GLUT4 translocation?
Assessment of GLUT4 translocation in muscle and muscle cell lines has revealed insulin-stimulated increases at the cell surface of between two- and sixfold in human and rat muscles, respectively, in which the levels of cell surface GLUT4 were measured using affinity labelling approaches [29,32, 33, 34].
What are GLUT receptors?
Glucose transporter (GLUT) is a facilitative transport protein involved in glucose translocation across the cell membrane. From: Ocular Transporters and Receptors, 2013.
Which glut is insulin independent?
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 GLUT4 and insulin receptor?
GLUT4 is the insulin-responsive glucose transporter responsible for postprandial glucose clearance. In muscle and adipose cells, GLUT4 is packaged in vesicles that are released upon stimulation of the insulin receptor and, in the case of muscle, also in response to exercise (Bryant et al., 2002).
What kind of downstream pathways may get activated when insulin binds to the receptor?
Insulin binds to its receptor (IR) enhancing cell growth and proliferation via activation of the ERK/MAPK pathway. Insulin-IR complex also activates IRS/PI3K/AKT pathway that plays a crucial role in the glucose, protein and lipid metabolism.
What is the role of insulin and the GLUT4 transporter in glycolysis in skeletal muscle?
The major cellular mechanism for disposal of an exogenous glucose load is insulin-stimulated glucose transport into skeletal muscle. Skeletal muscle both stores glucose as glycogen and oxidizes it to produce energy following the transport step.
Which glut transporters are insulin independent?
Abstract. The glucose transport proteins (GLUT1 and GLUT4) facilitate glucose transport into insulin-sensitive cells. GLUT1 is insulin-independent and is widely distributed in different tissues.