Rnd3 is a small (~21 kDa) signaling
G protein
G proteins, also known as guanine nucleotide-binding proteins, are a family of proteins that act as molecular switches inside cells, and are involved in transmitting signals from a variety of stimuli outside a cell to its interior. Their a ...
(to be specific, a
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 ...
), and is a member of the
Rnd subgroup of the
Rho family of GTPases
The Rho family of GTPases is a family of small (~21 kDa) signaling G proteins, and is a subfamily of the Ras superfamily. The members of the Rho GTPase family have been shown to regulate many aspects of intracellular actin dynamics, and are foun ...
.
It is encoded by the gene RND3.
Like other members of the Rho family of
Ras-related GTPases it regulates the organization of the actin cytoskeleton in response to extracellular growth factors.
Regulation
Most Rho family members cycle between an inactive GDP-bound form and an active GTP-bound form. However, members of the Rnd subgroup of the Rho family are exceptions to this, binding detectably only to GTP, while having low GTPase activity, if any. Instead, Rnd family proteins are regulated through other mechanisms that control their
production
Production may refer to:
Economics and business
* Production (economics)
* Production, the act of manufacturing goods
* Production, in the outline of industrial organization, the act of making products (goods and services)
* Production as a stati ...
,
degradation
Degradation may refer to:
Science
* Degradation (geology), lowering of a fluvial surface by erosion
* Degradation (telecommunications), of an electronic signal
* Biodegradation of organic substances by living organisms
* Environmental degradatio ...
,
phosphorylation, and
localization.
Interactions
In its GTP-bound form, RhoA exposes regions that allow it to interact with downstream targets. Rnd3 contains a region which is similar to the one RhoA exposes for
interaction
Interaction is action that occurs between two or more objects, with broad use in philosophy and the sciences. It may refer to:
Science
* Interaction hypothesis, a theory of second language acquisition
* Interaction (statistics)
* Interactions o ...
with
ROCK1
ROCK1 is a protein serine/threonine kinase also known as rho-associated, coiled-coil-containing protein kinase 1. Other common names are ROKβ and P160ROCK. ROCK1 is a major downstream effecter of the small GTPase RhoA and is a regulator of the a ...
, allowing Rnd3 to compete with RhoA for interaction with ROCK1. By binding to ROCK1, Rnd3 inhibits it from
phosphorylating downstream targets necessary for
stress fiber
Stress fibers are contractile actin bundles found in non-muscle cells. They are composed of actin (microfilaments) and non-muscle myosin II (NMMII), and also contain various crosslinking proteins, such as α-actinin, to form a highly regulated ...
formation. Rnd3 is also directly involved in controlling RhoA activity through suppression of
PLEKHG5 and activation of
ARHGAP5
Rho GTPase-activating protein 5 is an enzyme that in humans is encoded by the ''ARHGAP5'' gene.
Function
Rho GTPase activating protein 5 negatively regulates RHO GTPases, a family that may mediate cytoskeleton changes by stimulating the hydrol ...
.
Interaction with
UBXD5 has also been shown.
References
Further reading
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