Transforming growth factor beta superfamily

The transforming growth factor beta (TGF-β) superfamily is a large family of structurally related cell regulatory proteins that was named after its first member, TGF-β1, originally described in 1983.

Many proteins have since been described as members of the TGF-β superfamily in a variety of species, including invertebrates as well as vertebrates and categorized into 23 distinct gene types that fall into four major subfamilies:.


 * the decapentaplegic-Vg-related (DVR) related subfamily (including the bone morphogenetic proteins and the growth differentiation factors)


 * the activin/inhibin subfamily


 * the TGF-β subfamily


 * a group encompassing various divergent members

Transforming growth factor-beta (TGF-beta) is a multifunctional peptide that controls proliferation, differentiation and other functions in many cell types. TGF-beta-1 is a peptide of 112 amino acid residues derived by proteolytic cleavage from the C-terminal of a precursor protein.

These molecules interact with a conserved family of cell surface serine/threonine-specific protein kinase receptors, and generate intracellular signals using a conserved family of proteins called SMADs. They play fundamental roles in the regulation of basic biological processes such as growth, development, tissue homeostasis and regulation of the immune system.

Structure
Proteins from the TGF-beta family are only active as homo- or heterodimer; the two chains being linked by a single disulphide bond. From X-ray studies of TGF-beta-2, it is known that all the other cysteines are involved in intrachain disulphide bonds. As shown in the following schematic representation, there are four disulphide bonds in the TGF-beta's and in inhibin beta chains, while the other members of this family lack the first bond.

interchain |          +--|+           |                                          || xxxxcxxxxxCcxxxxxxxxxxxxxxxxxxCxxCxxxxxxxxxxxxxxxxxxxCCxxxxxxxxxxxxxxxxxxxCxCx |     |                  |  |                                        | |     +--+                  +--|+ |                                  +--+

'C': conserved cysteine involved in a disulphide bond.

Human proteins containing this domain
AMH;      ARTN;      BMP10;     BMP15;     BMP2;      BMP3;      BMP4;      BMP5; BMP6;      BMP7;      BMP8A;     BMP8B;     GDF1;      GDF10;     GDF11;     GDF15; GDF2;     GDF3;      GDF3A;     GDF5;      GDF6;      GDF7;      GDF8;      GDF9; GDNF;      INHA;      INHBA;     INHBB;     INHBC;     INHBE;     LEFTY1;    LEFTY2; MSTN;     NODAL;     NRTN;      PSPN;      TGFB1; TGFB2;     TGFB3;