Only asparagine residues in the tripeptide sequences Asn-X-Ser and Asn-X-Thr (where X is any amino acid except proline) are substrates for oligosaccharyl transferase.

TLS Online TPP Program

#Id: 8226

#Section 3: Genetics, Cellular and Molecular Biology

I-cell disease

• almost all of the hydrolytic enzymes are missing from the lysosomes of many cell types.

• mis-sorting has been traced to a defective or missing GlcNAc phosphotransferase.

TLS Online TPP Program

#Id: 8225

#Section 3: Genetics, Cellular and Molecular Biology

Hurler’s disease- mutation in a structural gene that codes for an individual lysosomal hydrolase.

TLS Online TPP Program

#Id: 8224

#Section 3: Genetics, Cellular and Molecular Biology

Lysosomal storage diseases:

• Hurler’s disease

• Inclusion-cell disease

TLS Online TPP Program

#Id: 8223

#Section 3: Genetics, Cellular and Molecular Biology

Retromer

a coat protein complex specialized for endosome-to-TGN transport, recycle the M6P receptor to the TGN

TLS Online TPP Program

#Id: 8221

#Section 3: Genetics, Cellular and Molecular Biology

The M6P receptor protein binds to M6P at pH 6.5–6.7 in the TGN lumen and releases it at pH 6, in the lumen of endosomes.

TLS Online TPP Program

#Id: 8219

#Section 3: Genetics, Cellular and Molecular Biology

M6P residues are generated in the cis-Golgi by two Golgi-resident enzymes. 

1. N-acetylglucosamine (GlcNAc) phosphotransferase
2. Phosphodiesterase