N-acetylglucosamine-1-phosphate transferase
# N-acetylglucosamine-1-phosphate transferase

N-acetylglucosamine-1-phosphate transferase is a transferase enzyme.

## Function

It is made up of two alpha (α), two betas (β), and two gammas (γ) subunits. GNPTAB produces the alpha and beta subunits, GNPTG produces the gamma subunit. GlcNAc-1-phosphotransferase functions to prepare newly made enzymes for lysosome transportation (lysosomal hydrolases to the lysosome). Lysosomes, a part of an animal cell, helps break down large molecules into smaller ones that can be reused. GlcNAc-1-phosphotransferase phosphorylates carbon 6 of one or more mannosyl residues of N linked glycoproteins being processed in Golgi Apparatus . UDP-GLcNAc provides the phosphate in a reaction catalysed by this enzyme. M6P acts as an indicator of whether a hydrolase should be transported to the lysosome or not. Once a hydrolase indicates an M6P, it can be transported to a lysosome. Surprisingly some lysosomal enzymes are only tagged at a rate of 5% or lower.

## Clinical significance

It is associated with the following conditions:

* mucolipidosis II alpha/beta (I-cell disease) - GNPTAB
* mucolipidosis III alpha/beta (pseudo-Hurler polydystrophy) - GNPTAB
* mucolipidosis III gamma - GNPTG
* stuttering (Kang et al., 2010)

In melanocytic cells, GNPTG gene expression may be regulated by MITF.

