ADAM10
Encyclopedia
Disintegrin and metalloproteinase domain-containing protein 10, also known as ADAM10 or CDw156 or CD156c is a protein
that in humans is encoded by the ADAM10 gene
.
and protease
domain
s. Sheddase, a generic name for the ADAM metallopeptidase, functions primarily to cleave membrane proteins at the cellular surface. Once cleaved, the sheddases release soluble ectodomains with an altered location and function.
Although a single sheddase may “shed” a variety of substances, multiple sheddases can cleave the same substrate resulting in different consequences.This gene encodes an ADAM family member that cleaves many proteins including TNF-alpha and E-cadherin.
ADAM10 (EC#: 3.4.24.81) is a sheddase
, and has a broad specificity for peptide hydrolysis reactions.
ADAM10 cleaves ephrin
, within the ephrin/eph complex, formed between two cell surfaces. When ephrin is freed from the opposing cell, the entire ephrin/eph complex is endocytosed. This shedding in trans had not been previously shown, but may well be involved in other shedding events.
The proposed active site of ADAM10 has been identified by sequence analysis, and is identical to enzymes in the Snake Venom metalloprotein domain family. The consensus sequence for catalytically active ADAM proteins is HEXGHNLGXXHD. Structural analysis of ADAM17, which has the same active site sequence as ADAM10, suggests that the three histidines in this sequence bind a Zn2+ atom, and that the glutamate is the catalytic residue.
In the image of the active site shown above, the catalytic glutamate residue is on the left, and the zinc (light blue) is shown coordinated to three histidine residues. An inhibitor is bound to the active site, which is shown extending out of frame from the active site.
In zinc proteases, the key catalytic elements have been identified as a glutamate residue and a Zn2+ ion coordinated to histidine residues.
The proposed mechanism begins with deprotonation of a water molecule by glutamate. The resultant hydroxide initiates a nucleophillic attack on a carbonyl carbon on the peptide backbone, producing a tetrahedral intermediate. This step is facilitated by electron withdrawal from oxygen by Zn2+ and by zinc’s subsequent stabilization of the negative charge on the oxygen atom in the intermediate state. As electrons move down from the oxygen atom to re-form the double bond, the tetrahedral intermediate collapses to products with protonation of -NH by the glutamate residue.
malaria parasites help the invaders bind to red blood cells. But once attached to host blood cells, the parasites need to shed the 'sticky' surface proteins that would otherwise interfere with entrance into the cell. The Sheddase enzyme, specifically called PfSUB2 in this example, is required for the parasites to invade cells; without it, the parasites die. The sheddase is stored in and released from cellular compartments near the tip of the parasite, according to the study. Once on the surface, the enzyme attaches to a motor that shuttles it from front to back, liberating the sticky surface proteins. With these proteins removed, the parasite gains entrance into a red blood cell. The entire invasion lasts about 30 seconds and without this ADAM metallopeptidase, malaria would be ineffective at invading the red blood cells.
over-expressing cell lines while inhibitors, that do not inhibit ADAM10, have no impact. These results are consistent with ADAM10 being a major determinant of HER2 shedding, the inhibition of which, may provide a novel therapeutic approach for treating breast cancer and a variety of other cancers with active HER2 signaling.
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
that in humans is encoded by the ADAM10 gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
.
Function
Members of the ADAM family are cell surface proteins with a unique structure possessing both potential adhesionCell adhesion
Cellular adhesion is the binding of a cell to a surface, extracellular matrix or another cell using cell adhesion molecules such as selectins, integrins, and cadherins. Correct cellular adhesion is essential in maintaining multicellular structure...
and protease
Protease
A protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein....
domain
Protein domain
A protein domain is a part of protein sequence and structure that can evolve, function, and exist independently of the rest of the protein chain. Each domain forms a compact three-dimensional structure and often can be independently stable and folded. Many proteins consist of several structural...
s. Sheddase, a generic name for the ADAM metallopeptidase, functions primarily to cleave membrane proteins at the cellular surface. Once cleaved, the sheddases release soluble ectodomains with an altered location and function.
Although a single sheddase may “shed” a variety of substances, multiple sheddases can cleave the same substrate resulting in different consequences.This gene encodes an ADAM family member that cleaves many proteins including TNF-alpha and E-cadherin.
ADAM10 (EC#: 3.4.24.81) is a sheddase
Sheddase
Sheddases are membrane-bound enzymes that cleave extracellular portions of transmembrane proteins, releasing the soluble ectodomains from the cell surface...
, and has a broad specificity for peptide hydrolysis reactions.
ADAM10 cleaves ephrin
Eph receptor
Eph receptors are components of cell signalling pathways involved in animal growth and development, forming the largest sub-family of receptor tyrosine kinases . The extracellular domain of an Eph receptor interacts with ephrin ligands, which may be tethered to neighbouring cells...
, within the ephrin/eph complex, formed between two cell surfaces. When ephrin is freed from the opposing cell, the entire ephrin/eph complex is endocytosed. This shedding in trans had not been previously shown, but may well be involved in other shedding events.
Structure
Although no crystallographic x-ray diffraction analyses have been published that depict the entire structure of ADAM10, one domain has been studied using this technique. The disintigrin and cysteine-rich domain (shown to the right) plays an essential role in regulation of protease activity in vivo. Recent experimental evidence suggests that this region, which is distinct from the active site, may be responsible for substrate specificity of the enzyme. It is proposed that this domain binds to particular regions of the enzyme’s substrate, allowing peptide bond hydrolysis to occur in well defined locations on certain substrate proteins.The proposed active site of ADAM10 has been identified by sequence analysis, and is identical to enzymes in the Snake Venom metalloprotein domain family. The consensus sequence for catalytically active ADAM proteins is HEXGHNLGXXHD. Structural analysis of ADAM17, which has the same active site sequence as ADAM10, suggests that the three histidines in this sequence bind a Zn2+ atom, and that the glutamate is the catalytic residue.
In the image of the active site shown above, the catalytic glutamate residue is on the left, and the zinc (light blue) is shown coordinated to three histidine residues. An inhibitor is bound to the active site, which is shown extending out of frame from the active site.
Catalytic Mechanism
Although the exact mechanism of ADAM10 has not been thoroughly investigated, its active site is homologous to those of well studied zinc-proteases such as carboxypeptidase A and thermolysin. Therefore it is proposed that ADAM10 utilizes a similar mechanism as these enzymes.In zinc proteases, the key catalytic elements have been identified as a glutamate residue and a Zn2+ ion coordinated to histidine residues.
The proposed mechanism begins with deprotonation of a water molecule by glutamate. The resultant hydroxide initiates a nucleophillic attack on a carbonyl carbon on the peptide backbone, producing a tetrahedral intermediate. This step is facilitated by electron withdrawal from oxygen by Zn2+ and by zinc’s subsequent stabilization of the negative charge on the oxygen atom in the intermediate state. As electrons move down from the oxygen atom to re-form the double bond, the tetrahedral intermediate collapses to products with protonation of -NH by the glutamate residue.
Interaction with the malaria parasite
A number of different proteins on the surface of Plasmodium falciparumPlasmodium falciparum
Plasmodium falciparum is a protozoan parasite, one of the species of Plasmodium that cause malaria in humans. It is transmitted by the female Anopheles mosquito. Malaria caused by this species is the most dangerous form of malaria, with the highest rates of complications and mortality...
malaria parasites help the invaders bind to red blood cells. But once attached to host blood cells, the parasites need to shed the 'sticky' surface proteins that would otherwise interfere with entrance into the cell. The Sheddase enzyme, specifically called PfSUB2 in this example, is required for the parasites to invade cells; without it, the parasites die. The sheddase is stored in and released from cellular compartments near the tip of the parasite, according to the study. Once on the surface, the enzyme attaches to a motor that shuttles it from front to back, liberating the sticky surface proteins. With these proteins removed, the parasite gains entrance into a red blood cell. The entire invasion lasts about 30 seconds and without this ADAM metallopeptidase, malaria would be ineffective at invading the red blood cells.
Breast cancer
In combination with low doses of herceptin, selective ADAM10 inhibitors decrease proliferation in HER2HER2/neu
HER-2 also known as proto-oncogene Neu, receptor tyrosine-protein kinase erbB-2, CD340 or p185 is an enzyme that in humans is encoded by the ERBB2 gene. Over expression of this gene is correlated with higher aggressiveness in breast cancers...
over-expressing cell lines while inhibitors, that do not inhibit ADAM10, have no impact. These results are consistent with ADAM10 being a major determinant of HER2 shedding, the inhibition of which, may provide a novel therapeutic approach for treating breast cancer and a variety of other cancers with active HER2 signaling.
See also
- Cluster of differentiationCluster of differentiationThe cluster of differentiation is a protocol used for the identification and investigation of cell surface molecules present on white blood cells, providing targets for immunophenotyping of cells...
- ADAM 17 MetallopeptidaseADAM17ADAM metallopeptidase domain 17 , also called TACE , is a 70-kDa enzyme that belongs to the ADAM protein family of disintegrins and metalloproteases.- Chemical characteristics :...
- ADAM ProteinADAM ProteinADAM is a family of peptidase proteins. It is also known as the adamalysin family or MDC family. ADAMs are classified as sheddases because they cut off or shed extracellular portions of transmembrane proteins. For example, ADAM10 can cut off part of the HER2 receptor, activating it...