Signal transducing adaptor proteins (STAPs) are

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

s that are accessory to main proteins in a

signal transduction Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellula ...

pathway. Adaptor proteins contain a variety of protein-binding modules that link protein-binding partners together and facilitate the creation of larger signaling complexes. These proteins tend to lack any intrinsic enzymatic activity themselves, instead mediating specific protein–protein interactions that drive the formation of

protein complexes A protein complex or multiprotein complex is a group of two or more associated polypeptide chains. Protein complexes are distinct from multienzyme complexes, in which multiple catalytic domains are found in a single polypeptide chain. Protein c ...

. Examples of adaptor proteins include MYD88, Grb2 and

SHC1 SHC-transforming protein 1 is a protein that in humans is encoded by the ''SHC1'' gene. SHC has been found to be important in the regulation of apoptosis and drug resistance in mammalian cells. SCOP classifies the 3D structure as belonging to th ...

Signaling components

Much of the specificity of

depends on the recruitment of several signalling components such as protein kinases and G-protein

GTPase GTPases are a large family of hydrolase enzymes that bind to the nucleotide guanosine triphosphate (GTP) and hydrolyze it to guanosine diphosphate (GDP). The GTP binding and hydrolysis takes place in the highly conserved P-loop "G domain", a pro ...

s into short-lived active complexes in response to an activating signal such as 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 regu ...

binding to its

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 ...

Domains

Adaptor proteins usually contain several domains within their structure (e.g., Src homology 2 (SH2) and

SH3 domain The SRC Homology 3 Domain (or SH3 domain) is a small protein domain of about 60 amino acid residues. Initially, SH3 was described as a conserved sequence in the viral adaptor protein v-Crk. This domain is also present in the molecules of phos ...

s) that allow specific interactions with several other specific proteins. SH2 domains recognise specific amino acid sequences within proteins containing

phosphotyrosine -Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid with a polar side group. The word "tyrosine" is from the Gr ...

residues and SH3 domains recognise

proline Proline (symbol Pro or P) is an organic acid classed as a proteinogenic amino acid (used in the biosynthesis of proteins), although it does not contain the amino group but is rather a secondary amine. The secondary amine nitrogen is in the prot ...

-rich sequences within specific peptide sequence contexts of proteins. There are many other types of interaction domains found within adaptor and other signalling proteins that allow a rich diversity of specific and coordinated protein–protein interactions to occur within the cell during

Genes

Genes encoding adaptor proteins include: *

BCAR3 Breast cancer anti-estrogen resistance protein 3 is a protein that in humans is encoded by the ''BCAR3'' gene. Function Breast tumors are initially dependent on estrogens for growth and progression and can be inhibited by anti-estrogens such a ...

– Breast cancer anti-estrogen resistance protein 3 * CBL – Casitas B-lineage Lymphoma *

FRS2 Fibroblast growth factor receptor substrate 2 is a protein that in humans is encoded by the ''FRS2'' gene. FRS2 is an 80 kDa membrane-anchored signal transducing adaptor protein (STAP) that links specific activated Receptor Tyrosine Kinases (RTKs) ...

– Fibroblast growth factor receptor substrate 2 *

GAB2 GRB2-associated-binding protein 2 also known as GAB2 is a protein that in humans is encoded by the ''GAB2'' gene. GAB2 is a docking protein with a conserved, folded PH domain attached to the membrane and a large disordered region, which hosts int ...

– GRB2-associated binding protein 2 *

GRAP GRB2-related adapter protein is a protein that in humans is encoded by the ''GRAP'' gene. This gene encodes a member of the GRB2/Sem5 ('' C. elegans'' homolog)/Drk (''Drosophila'' homolog) family. This member functions as a cytoplasmic signalin ...

– GRB2-related adaptor protein *

GRAP2 GRB2-related adapter protein 2 also known as GRB2-related adaptor downstream of Shc (GADS) is a 37 kDa protein that in humans is encoded by the ''GRAP2'' gene. Function This gene encodes a member of the GRB2/Sem5/Drk family. This member is an ...

– GRB2-related adaptor protein 2 * GRB2 – Growth factor receptor-bound protein 2 *

IRS1 Insulin receptor substrate 1 (IRS-1) is a signaling adapter protein that in humans is encoded by the ''IRS-1'' gene. It is a 131 kDa protein with amino acid sequence of 1242 residues. It contains a single pleckstrin homology (PH) domain at the N-te ...

– Insulin receptor substrate 1 *

LDLRAP1 Low-density lipoprotein receptor adapter protein 1 is a protein that in humans is encoded by the ''LDLRAP1'' gene. The protein encoded by this gene is a cytosolic protein which contains a phosphotyrosine binding (PTB) domain. The PTB domain has b ...

– low-density lipoprotein receptor adaptor protein 1 * MYD88 - Myeloid differentiation primary response gene 88 *

NCDN Neurochondrin (also known as its murine homologue, Norbin) is a protein that in humans is encoded by the ''NCDN'' gene. This gene encodes a leucine-rich cytoplasmic protein, which is highly similar to a mouse protein norbin that negatively regula ...

- Neurochondrin *

NCK1 Cytoplasmic protein NCK1 is a protein that in humans is encoded by the ''NCK1'' gene. Gene The Nck (non-catalytic region of tyrosine kinase adaptor protein 1) belongs to the adaptor family of proteins. The nck gene was initially isolated from ...

– NCK adaptor protein 1 *

NCK2 Cytoplasmic protein NCK2 (also known as NCK-beta and Grb4) is a protein that in humans is encoded by the ''NCK2'' gene. Function NCK belongs to family of adaptor proteins. There are two mammalian NCK genes, NCK1 and NCK2. NCK1 is located in ch ...

– NCK adaptor protein 2 *

NOS1AP Nitric oxide synthase 1 adaptor protein (NOS1AP) also known as carboxyl-terminal PDZ ligand of neuronal nitric oxide synthase protein (CAPON) is a protein that in humans is encoded by the ''NOS1AP'' gene. This gene encodes a cytosolic protein tha ...

– nitric oxide synthase 1 (neuronal) adaptor protein *

PIK3AP1 Phosphoinositide 3-kinase adapter protein 1 is an enzyme that in humans is encoded by the ''PIK3AP1'' gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meani ...

– phosphoinositide-3-kinase adaptor protein 1 *

SH2B1 SH2B adapter protein 1 is a protein that in humans is encoded by the ''SH2B1'' gene. Interactions SH2B1 has been shown to interact with: * Grb2, * Insulin receptor, * Janus kinase 2, and * TrkA. Clinical significance Variations close to ...

– SH2B adaptor protein 1 *

SH2B2 SH2B adapter protein 2 is a protein that in humans is encoded by the ''SH2B2'' gene. Function The protein encoded by this gene is expressed in B lymphocytes and contains pleckstrin homology and src homology 2 (SH2) domains. In Burkitt lymphoma ...

– SH2B adaptor protein 2 *

SH2B3 SH2B adapter protein 3 (SH2B3), also known as lymphocyte adapter protein (LNK), is a protein that in humans is encoded by the ''SH2B3'' gene on chromosome 12. SH2B adapter protein 3 is a protein that in humans is encoded by the SH2B3 gene on chrom ...

– SH2B adaptor protein 3 *

SH2D3A SH2 domain-containing protein 3A is a protein that in humans is encoded by the ''SH2D3A'' gene. The protein may be useful in Western Blots and ELISAs. Interactions SH2D3A has been shown to interact with the epidermal growth factor receptor ...

-SH2 domain containing 3A *

SH2D3C SH2 domain containing 3C, also known as SH2D3C, is a protein that in humans is encoded by the ''SH2D3C'' gene. Function Sh2d3c is a gene on human chromosome 9 that encodes an SH2 domain containing protein known as NSP3. The mouse homologue is ...

– SH2 domain containing 3C *

SNTA1 Alpha-1-syntrophin is a protein that in humans is encoded by the ''SNTA1'' gene. Alpha-1 syntrophin is a signal transducing adaptor protein and serves as a scaffold for various signaling molecules. Alpha-1 syntrophin contains a PDZ domain, two Ple ...

– Syntrophin, alpha 1 * SHB – Src homology 2 domain containing adaptor protein B * SLC4A1AP – solute carrier family 4 (anion exchanger), member 1, adaptor protein

Signaling components

Domains

Genes

See also

References

Further reading