Muscle cells have an abundant, modified smooth ER called the sarcoplasmic reticulum.

The release and reuptake of Ca2+ by the sarcoplasmic reticulum trigger myofibril contraction and relaxation, respectively

TLS Online TPP Program

#Id: 7950

#Section 3: Genetics, Cellular and Molecular Biology

Prior to transfer to a nascent chain in the lumen of the  ER, the oligosaccharide precursor is assembled on amembrane- attached anchor called dolichol phosphate, a longchain polyisoprenoid lipid

TLS Online TPP Program

#Id: 7949

#Section 3: Genetics, Cellular and Molecular Biology

A branched oligosaccharide containing

3 glucose (Glc)

9 mannose (Man)

2 N-acetylglucosamine (GlcNAc)

Glc3Man9(GlcNAc)2

TLS Online TPP Program

#Id: 7948

#Section 3: Genetics, Cellular and Molecular Biology

Biosynthesis of all N-linked oligosaccharides begins in the rough ER with a preformed oligosaccharide precursor containing 14 residues.

TLS Online TPP Program

#Id: 7947

#Section 3: Genetics, Cellular and Molecular Biology

N-linked oligosaccharides

carbohydrate chains attached to the amide nitrogen of asparagine

TLS Online TPP Program

#Id: 7946

#Section 3: Genetics, Cellular and Molecular Biology

O-linked oligosaccharides

Carbohydrate chains in glycoproteins attached to the

hydroxyl group (-OH) in serine and threonine residues

TLS Online TPP Program

#Id: 7945

#Section 3: Genetics, Cellular and Molecular Biology

Glycoproteins

Proteins with attached carbohydrates