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 proteins 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 under biological conditions), 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 mechanism of action of a ...

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: *

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 In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian u ...

* RAP2A, RAP2B, RAP1C * RAB5C

References

External links

* EC 3.6.5 Peripheral membrane proteins {{membrane-protein-stub