The Rho family of GTPases is a family of small G proteins. The members of the Rho GTPase family have been shown to regulate many aspects of intracellular actin dynamics, and are found in all eukaryotic kingdoms, including yeasts and some plants.

1. Rho family of GTPases
Bardia Farivar
Department of Medical Biology
Istanbul University
Cerrahpaşa Medical Faculty

2. Rho family of GTPases
The Rho family of GTPases is a family of small (~21 kDa) G
proteins. The members of the Rho GTPase family have been shown
to regulate many aspects of intracellular actin dynamics, and are
found in all eukaryotic kingdoms, including yeasts and some plants.

3. Three members of the family have been studied in detail:
CDC42, Rac1, and Rho.
Rho proteins play a role in organelle development, cytoskeletal dynamics,
cell movement, and other common cellular functions.

4. The functions of these GTPases have been primarily investigated with
regard to their effects of actin filaments. Rho regulates stress fiber
formation and cell contraction.
Rho family GTPases also modulate microtubule dynamics and cell
polarity.

5. CDC42
Cell Division Control protein 42 homolog, also known as
CDC42, is a protein involved in regulation of the cell cycle.
It was originally identified in S. cerevisiae (yeast) as a
mediator of cell division, and is now known to influence a
variety of signaling events and cellular processes in a variety
of organisms from yeast to mammals.

6. Function
Human CDC42 is a small GTPase of the Rho family, which regulates
signaling pathways that control diverse cellular functions including
cell morphology, cell migration, endocytosis and cell cycle
progression.

7. Structure
CDC42 is a homodimer. Its total length is 191 amino acids and its
theoretical weight is 21.33 KDa. Its sequence domains include a
P-loop containing nucleoside triphosphate hydrolase and a small
GTP-binding protein domain.

8. CDC42 cycles between an active GTP-bound state and an inactive
GDP-bound state. This process is regulated by guanine nucleotide
exchange factors (GEFs) which promote GTPase activating proteins
(GAPs) which increase GTP hydrolysis activity, and GTDP dissociation
inhibitors which inhibit the dissociation of the nucleotide from the
GTPase.

9. RAC1
Rac1 is a protein found in human cells. It is encoded by the RAC1
gene. This gene can produce a variety of alternatively spliced versions
of the Rac1 protein, which appear to carry out different functions.

10. Function
Rac1 is a small (~21 kDa) G protein (more specifically a GTPase), and is
a member of the Rac subfamily of the family Rho family of GTPases.
Members of this superfamily appear to regulate a diverse array of cellular
events, including the glucose uptake, cell growth, cytoskeletal
reorganization, antimicrobial cytotoxicity, and the activation of protein
kinases.