CELL BIOLOGY CH. 12 Know how the SecATPase and BiP play in translocation in ER (

Question

CELL BIOLOGY CH. 12

Know how the SecATPase and BiP play in translocation in ER (figure 12.41).

Know the difference between single and multipass trans-membrane proteins in ER

(see figures 12.42-12.45)

How are transmembrane proteins glycosylated in ER?

What is the function of a GPI anchor?

How are lipids made in the ER?

What lipids make in the ER are precursors for Golgi?

What is the difference and how are lipids flipped in ER membrane and plasma membrane?

Alberts.-.Molecular.Biology.Of.The.Cell.5th.Ed IS THE TEXT

Explanation / Answer

1. . BiP is also an essential component of the translocation machinery, as well as playing a role in retrograde transport of proteins across the ER membrane. Transport of aberrant proteins destined for degradation by the proteasome.

3. glycosylation reactions occur in the lumen of the ER; others, in the lumina of the cis-, medial-, or trans-Golgi cisternae. Thus the presence of certain carbohydrate residues on proteins provide useful markers for following their movement from the ER and through the Golgi cisternae.

4. Glycophosphatidylinositol GPI generates diacylglycerol and inositol phosphate.

5. endoplasmic reticulum compartment is a central site for membrane lipid biogenesis, and examples of the emerging relationships between alterations in lipid composition, regulation of membrane lipid biogenesis, and cellular secretory function are also seen here.

6.The rough ER is a sort of mail room for proteins- proteins that get sent to the ER, are sorted according to their destinations, then forwarded to the appropriate cellular compartment (for some proteins, further sorting occurs in the Golgi apparatus, as well).

7. Flippases (rarely, flipases) are a family of transmembrane lipid transporter enzymes located in the membrane responsible for aiding the movement of phospholipid molecules between the two leaflets that compose a cell's membrane (transverse diffusion). Although phospholipids diffuse rapidly in the plane of the membrane, their polar head groups cannot pass easily through the hydrophobic center of the bilayer, limiting their diffusion in this dimension. Phospholipid molecules that are synthesized in the cell are incorporated into the cytoplasmic face of the membrane, where flippases can transfer them to the exoplasmic face.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.