Rap GTP-binding protein also known as Ras-related proteins or simply RAP is a type of
small GTPase
Small GTPases (), also known as small G-proteins, are a family of hydrolase enzymes that can bind and hydrolyze guanosine triphosphate (GTP). They are a type of G-protein found in the cytosol that are homologous to the alpha subunit of heterotrim ...
, similar in structure to
Ras.
These proteins share approximately 50% amino acid identity with the classical
RAS protein
Ras, from "Rat sarcoma virus", is a family of related proteins that are expressed in all animal cell lineages and organs. All Ras protein family members belong to a class of protein called small GTPase, and are involved in transmitting signals ...
s and have numerous structural features in common. The most striking difference between RAP proteins and RAS proteins resides in their 61st amino acid:
glutamine
Glutamine (symbol Gln or Q) is an α-amino acid that is used in the biosynthesis of proteins. Its side chain is similar to that of glutamic acid, except the carboxylic acid group is replaced by an amide. It is classified as a charge-neutral ...
in RAS is replaced by
threonine
Threonine (symbol Thr or T) is an amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form when dissolved in water), a carboxyl group (which is in the deprotonated −COO− ...
in RAP proteins. RAP counteracts the
mitogenic
A mitogen is a small bioactive protein or peptide that induces a cell to begin cell division, or enhances the rate of division (mitosis). Mitogenesis is the induction (triggering) of mitosis, typically via a mitogen.
The cell cycle
Mitogens ac ...
function of RAS because it can interact with RAS GAPs and RAF in a competitive manner.
Family members
Human genes that encode Ras-related proteins include:
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RAP1A
Ras-related protein Rap-1A is a protein that in humans is encoded by the ''RAP1A'' gene.
Function
The product of this gene belongs to the family of Ras-related proteins. These proteins share approximately 50% amino acid identity with the clas ...
,
RAP1B
Ras-related protein Rap-1b, also known as GTP-binding protein smg p21B, is a protein that in humans is encoded by the ''RAP1B'' gene.
References
Further reading
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{{gene-12-stub ...
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RAP2A
Ras-related protein Rap-2a is a protein that in humans is encoded by the ''RAP2A'' gene. RAP2A is a member of the Ras-related protein family.
Interactions
RAP2A has been shown to interact with RUNDC3A, RASSF5
Ras association domain-cont ...
,
RAP2B,
RAP2C
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RAB5C
Ras-related protein Rab-5C is a protein that in humans is encoded by the ''RAB5C'' gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that ...
References
External links
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EC 3.6.5
Peripheral membrane proteins
{{membrane-protein-stub