Gene Summary: KRAS acts as a molecular on/off switch. Once it is turned on it recruits and activates proteins necessary for the propagation of growth factor and other receptors' signal, such as c-Raf and PI 3-kinase. KRAS binds to GTP in the active state and possesses an intrinsic enzymatic activity which cleaves the terminal phosphate of the nucleotide converting it to GDP. Upon conversion of GTP to GDP, KRAS is turned off. The rate of conversion is usually slow but can be sped up dramatically by an accessory protein of the GTPase activating protein (GAP) class, for example RasGAP. In turn KRAS can bind to proteins of the Guanine Nucleotide Exchange Factor (GEF) class, for example SOS1, which forces the release of bound nucleotide. Subsequently, KRAS binds GTP present in the cytosol and the GEF is released from ras-GTP. Other members of the Ras family include: HRAS and NRAS. These proteins all are regulated in the same manner and appear to differ largely in their sites of action within General information above from NCBI
Enzyme regulation: Alternate between an inactive form bound to GDP and an active form bound to GTP. Activated by a guanine nucleotide-exchange factor (GEF) and inactivated by a GTPase- activating protein (GAP).
Subunit structure: Interacts with PHLPP. Interacts (active GTP-bound form preferentially) with RGS14 (By similarity).
Subcellular location: Cell membrane; Lipid-anchor; Cytoplasmic side.
Post-translational: Acetylation at Lys-104 prevents interaction with guanine nucleotide exchange factors (GEFs).
Involvement in disease: Leukemia, acute myelogenous (AML) [MIM:601626]: A subtype of acute leukemia, a cancer of the white blood cells. AML is a malignant disease of bone marrow characterized by maturational arrest of hematopoietic precursors at an early stage of development. Clonal expansion of myeloid blasts occurs in bone marrow, blood, and other tissue. Myelogenous leukemias develop from changes in cells that normally produce neutrophils, basophils, eosinophils and monocytes. Note=The disease is caused by mutations affecting the gene represented in this entry.
Leukemia, juvenile myelomonocytic (JMML) [MIM:607785]: An aggressive pediatric myelodysplastic syndrome/myeloproliferative disorder characterized by malignant transformation in the hematopoietic stem cell compartment with proliferation of differentiated progeny. Patients have splenomegaly, enlarged lymph nodes, rashes, and hemorrhages. Note=The disease is caused by mutations affecting the gene represented in this entry.
Noonan syndrome 3 (NS3) [MIM:609942]: A syndrome characterized by facial dysmorphic features such as hypertelorism, a downward eyeslant and low-set posteriorly rotated ears. Other features can include short stature, a short neck with webbing or redundancy of skin, cardiac anomalies, deafness, motor delay and variable intellectual deficits. Note=The disease is caused by mutations affecting the gene represented in this entry.
Gastric cancer (GASC) [MIM:613659]: A malignant disease which starts in the stomach, can spread to the esophagus or the small intestine, and can extend through the stomach wall to nearby lymph nodes and organs. It also can metastasize to other parts of the body. The term gastric cancer or gastric carcinoma refers to adenocarcinoma of the stomach that accounts for most of all gastric malignant tumors. Two main histologic types are recognized, diffuse type and intestinal type carcinomas. Diffuse tumors are poorly differentiated infiltrating lesions, resulting in thickening of the stomach. In contrast, intestinal tumors are usually exophytic, often ulcerating, and associated with intestinal metaplasia of the stomach, most often observed in sporadic disease. Note=The disease is caused by mutations affecting the gene represented in this entry.
Note=Defects in KRAS are a cause of pylocytic astrocytoma (PA). Pylocytic astrocytomas are neoplasms of the brain and spinal cord derived from glial cells which vary from histologically benign forms to highly anaplastic and malignant tumors.
Cardiofaciocutaneous syndrome 2 (CFC2) [MIM:615278]: A form of cardiofaciocutaneous syndrome, a multiple congenital anomaly disorder characterized by a distinctive facial appearance, heart defects and mental retardation. Heart defects include pulmonic stenosis, atrial septal defects and hypertrophic cardiomyopathy. Some affected individuals present with ectodermal abnormalities such as sparse, friable hair, hyperkeratotic skin lesions and a generalized ichthyosis-like condition. Typical facial features are similar to Noonan syndrome. They include high forehead with bitemporal constriction, hypoplastic supraorbital ridges, downslanting palpebral fissures, a depressed nasal bridge, and posteriorly angulated ears with prominent helices. CFC2 patients often do not have the skin abnormalities, such as ichthyosis, hyperkeratosis, and hemangioma observed in CFC1. Note=The disease is caused by mutations affecting the gene represented in this entry.
Note=KRAS mutations are involved in cancer development.
Sequence similarity: Belongs to the small GTPase superfamily. Ras family.
General information above from UniProt