GNPTG (“N-acetylglucosamine-1-phosphate transferase, gamma subunit.”) is a
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
in the human body. It is one of three genes that were found to correlate with
stuttering
Stuttering, also known as stammering, is a speech disorder in which the flow of speech is disrupted by involuntary repetitions and prolongations of sounds, syllables, words, or phrases as well as involuntary silent pauses or blocks in which the ...
.
Function
The GNPTG gene codes instructions for making the gamma subunit of an enzyme called GlcNAc-1-phosphotransferase (also called
N-acetylglucosamine-1-phosphate transferase). This enzyme is made up of two alpha (α), two beta (β), and two gamma (γ)
subunits. GNPTAB produces the alpha and beta subunits. GlcNAc-1-phosphotransferase functions to prepare newly made enzymes for lysosome transportation (lysosomal hydrolases to the lysosome).
Lysosome
A lysosome () is a membrane-bound organelle found in many animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane prot ...
s, a part of an animal cells, helps break down large molecules into smaller ones that can be reused. GlcNAc-1-phosphotransferase catalyzes the
''N''-linked glycosylation of asparagine residues with a molecule called
mannose-6-phosphate
Mannose-6-phosphate (M6P) is a molecule bound by lectin in the immune system. M6P is converted to fructose 6-phosphate by mannose phosphate isomerase.
M6P is a key targeting signal for acid hydrolase precursor proteins that are destined for transp ...
(M6P). M6P acts as indicator whether a hydrolase should be transported to the lysosome or not. Once a hydrolase has the indication from an M6P, it can be transported to a lysosome.
References
{{Reflist
Genes on human chromosome 16