A growth factor receptor is a

receptor Receptor may refer to: * Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a ...

that binds to a

growth factor A growth factor is a naturally occurring substance capable of stimulating cell proliferation, wound healing, and occasionally cellular differentiation. Usually it is a secreted protein or a steroid hormone. Growth factors are important for regul ...

. Growth factor receptors are the first stop in cells where the signaling cascade for cell differentiation and proliferation begins. Growth factors, which are

ligands In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electro ...

that bind to the receptor are the initial step to activating the growth factor receptors and tells the cell to grow and/or divide. These receptors may use the JAK/STAT,

MAP kinase A mitogen-activated protein kinase (MAPK or MAP kinase) is a type of protein kinase that is specific to the amino acids serine and threonine (i.e., a serine/threonine-specific protein kinase). MAPKs are involved in directing cellular responses ...

, and

PI3 kinase Phosphoinositide 3-kinases (PI3Ks), also called phosphatidylinositol 3-kinases, are a family of enzymes involved in cellular functions such as cell growth, proliferation, differentiation, motility, survival and intracellular trafficking, which i ...

pathways. A majority of growth factor receptors consists of receptor tyrosine kinases (RTKs). There are 3 dominant receptor types that are exclusive to research : the

epidermal growth factor receptor The epidermal growth factor receptor (EGFR; ErbB-1; HER1 in humans) is a transmembrane protein that is a receptor for members of the epidermal growth factor family (EGF family) of extracellular protein ligands. The epidermal growth factor recept ...

, the neurotrophin receptor, and the insulin receptors. All growth factor receptors are membrane bound and composed of 3 general protein domains:

extracellular This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices; for more specific and technical definitions ...

transmembrane A transmembrane protein (TP) is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the membrane. They frequentl ...

, and

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...

ic. The extracellular domain region is where a

ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...

may bind, usually with very high specificity. In RTKs, the binding of a ligand to the extracellular ligand binding site leads to the

autophosphorylation Autophosphorylation is a type of post-translational modification of proteins. It is generally defined as the phosphorylation of the kinase by itself. In eukaryotes, this process occurs by the addition of a phosphate group to serine, threoni ...

of tyrosine residues in the intracellular domain. These phosphorylations allow for other intracellular proteins to bind to with the

phosphotyrosine-binding domain In molecular biology, Phosphotyrosine-binding domains are protein domains which bind to phosphotyrosine. The phosphotyrosine-binding domain (PTB, also phosphotyrosine-interaction or PI domain) in the protein tensin tends to be found at the C-t ...

which results in a series of physiological responses within the cell.

Medical Relevance

Research in today’s society focus on growth factor receptors in order to pinpoint cancer treatment.

Epidermal growth factor receptor The epidermal growth factor receptor (EGFR; ErbB-1; HER1 in humans) is a transmembrane protein that is a receptor for members of the epidermal growth factor family (EGF family) of extracellular protein ligands. The epidermal growth factor recept ...

s are involved heavily with oncogene activity. Once growth factors bind to their receptor, a signal transduction pathway occurs within the cell to ensure the cell is working. However, in cancerous cells, the pathway might never turn on or turn off. Furthermore, in certain cancers, receptors (such as RTKs) are often observed to be overexpressed, which corresponds to the uncontrolled proliferation and differentiation of cells. For this same reason, tyrosine receptors are often a target for

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

therapy.

References

Receptors Single-pass transmembrane proteins {{biochem-stub