TGFβ receptors are single pass serine/threonine kinase receptors. They exist in several different isoforms that can be homo- or heterodimeric. The number of characterized ligands in the TGFβ superfamily far exceeds the number of known receptors, suggesting the promiscuity that exists between the ligand

Ligand

In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...

 and receptor interactions.

TGF can be found in many different tissue

Tissue (biology)

Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

 types, including brain, heart

Heart

The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

, kidney

Kidney

The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...

, liver

Liver

The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

, and testes. Over-expression

Gene expression

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...

 of TGF can induce renal fibrosis, causing kidney disease, as well as diabetes, and ultimately end-stage renal disease (ESRD). Recent developments have found that, using certain types of protein antagonist

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

s against TGFβ receptors, can halt and in some cases reverse the effects of renal fibrosis.

Classification

Three TGF-β receptor types can be distinguished by their structural and functional properties. Receptor types I and II have similar ligand-binding affinities and can be distinguished from each other only by peptide mapping. Both receptor types I and II have a high affinity for TGF-β1

TGF beta 1

Transforming growth factor beta 1 or TGF-β1 is a polypeptide member of the transforming growth factor beta superfamily of cytokines. It is a secreted protein that performs many cellular functions, including the control of cell growth, cell proliferation, cell differentiation and apoptosis...

 and low affinity for TGF-β2

TGF beta 2

Transforming growth factor-beta 2 is a secreted protein known as a cytokine that performs many cellular functions and has a vital role during embryonic development . It is an extracellular glycosylated protein...

. TGF-β receptor type III has a high affinity for both TGF-β1 and -β2 and in addition TGF-β1.2.

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