GNPTAB Antibody – Rabbit Polyclonal

This gene encodes two of three subunit types of the membrane-bound enzyme N-acetylglucosamine-1-phosphotransferase, a heterohexameric complex composed of two alpha, two beta, and two gamma subunits. The encoded protein is proteolytically cleaved at the Lys928-Asp929 bond to yield mature alpha and beta polypeptides while the gamma subunits are the product of a distinct gene (GeneID 84572). In the Golgi apparatus, the heterohexameric complex catalyzes the first step in the synthesis of mannose 6-phosphate recognition markers on certain oligosaccharides of newly synthesized lysosomal enzymes. These recognition markers are essential for appropriate trafficking of lysosomal enzymes. Mutations in this gene have been associated with both mucolipidosis II and mucolipidosis IIIA.[provided by RefSeq, May 2010]

GNPTAB: Catalyzes the formation of mannose 6-phosphate (M6P) markers on high mannose type oligosaccharides in the Golgi apparatus. M6P residues are required to bind to the M6P receptors (MPR), which mediate the vesicular transport of lysosomal enzymes to the endosomal/prelysosomal compartment. Defects in GNPTAB are the cause of mucolipidosis type II (MLII); also known as inclusion cell disease or I- cell disease (ICD). MLII is a fatal, autosomal recessive, lysosomal storage disorder characterized by severe clinical and radiologic features, peculiar fibroblast inclusions, and no excessive mucopolysacchariduria. Congenital dislocation of the hip, thoracic deformities, hernia, and hyperplastic gums are evident soon after birth. Defects in GNPTAB are the cause of mucolipidosis type III complementation group A (MLIIIA); also known as variant pseudo-Hurler polydystrophy. MLIIIA is an autosomal recessive disease of lysosomal enzyme targeting. Clinically MLIII is characterized by restricted joint mobility, skeletal dysplasia, and short stature. Mildly coarsened facial features and thickening of the skin have been described. Cardiac valvular disease and corneal clouding may also occur. Half of the reported patients show learning disabilities or mental retardation. Belongs to the stealth family. 2 isoforms of the human protein are produced by alternative splicing.

Protein type: Membrane protein, integral; EC 2.7.8.17; Transferase

Chromosomal Location of Human Ortholog: 12q23.2

Cellular Component: Golgi membrane; Golgi apparatus; integral to membrane; nucleus

Molecular Function: UDP-N-acetylglucosamine-lysosomal-enzyme N-acetylglucosaminephosphotransferase activity; calcium ion binding; transcription factor binding

Biological Process: lysosome organization and biogenesis; carbohydrate phosphorylation; protein secretion; cell differentiation

Disease: Mucolipidosis Iii Alpha/beta; Mucolipidosis Ii Alpha/beta