This gene encodes an endoplasmic reticulum-resident type II transmembrane glycosyltransferase involved in the chain elongation step of heparan sulfate biosynthesis. Mutations in this gene cause the type I form of multiple exostoses. [provided by RefSeq, Jul 2008]
Function:
Glycosyltransferase required for the biosynthesis of heparan-sulfate. The EXT1/EXT2 complex possesses substantially higher glycosyltransferase activity than EXT1 or EXT2 alone. Appears to be a tumor suppressor.
Subcellular Location:
Endoplasmic reticulum membrane. Golgi apparatus membrane. The EXT1/EXT2 complex is localized in the Golgi apparatus.
Tissue Specificity:
Ubiquitous.
DISEASE:
Defects in EXT1 are a cause of hereditary multiple exostoses type 1 (EXT1) [MIM:133700]. EXT is a genetically heterogeneous bone disorder caused by genes segregating on human chromosomes 8, 11, and 19 and designated EXT1, EXT2 and EXT3 respectively. EXT is a dominantly inherited skeletal disorder primarily affecting endochondral bone during growth. The disease is characterized by formation of numerous cartilage-capped, benign bone tumors (osteocartilaginous exostoses or osteochondromas) that are often accompanied by skeletal deformities and short stature. In a small percentage of cases exostoses have exhibited malignant transformation resulting in an osteosarcoma or chondrosarcoma. Osteochondromas development can also occur as a sporadic event.
Defects in EXT1 are a cause of tricho-rhino-phalangeal syndrome type 2 (TRPS2) [MIM:150230]. A syndrome that combines the clinical features of trichorhinophalangeal syndrome type 1 and multiple exostoses type 1. Affected individuals manifest multiple dysmorphic facial features including large, laterally protruding ears, a bulbous nose, an elongated upper lip, as well as sparse scalp hair, winged scapulae, multiple cartilaginous exostoses, redundant skin, and mental retardation. Note=A chromosomal aberration resulting in the loss of functional copies of TRPS1 and EXT1 has been found in TRPS2 patients.
Defects in EXT1 are a cause of chondrosarcoma (CHDSA) [MIM:215300]. It is a malignant neoplasm derived from cartilage cells. Chondrosarcomas range from slow-growing non-metastasizing lesions to highly aggressive metastasizing sarcomas.
Similarity:
Belongs to the glycosyltransferase 47 family.
SWISS:
Q16394
Gene ID:
2131
Database links:
Entrez Gene: 2131 Human
Entrez Gene: 14042 Mouse
Omim: 608177 Human
SwissProt: Q9JK82 Chinese Hamster
SwissProt: A5D7I4 Cow
SwissProt: Q16394 Human
SwissProt: P97464 Mouse
SwissProt: Q5RBC3 Orangutan
Unigene: 492618 Human
Unigene: 309395 Mouse
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