When a Membrane Protein Is Radioactively Labeled During Synthesis and Followed

question 6

Multiple Choice

When a membrane protein is radioactively labeled during synthesis and followed through the various organelles in the secretory pathway,all the radioactivity is concentrated in the cis-Golgi apparatus six hours after the protein synthesis.This suggests that the protein

• A)was imported directly into the cis-Golgi posttranslationally.
• B)contains a KDEL sequence near its C-terminus.
• C)has a membrane-spanning domain length equals the thickness of the cis-Golgi membrane.
• D)has a mannose-6-phosphate tag.
• E)is misfolded and being degraded in the cis-Golgi.

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Definitions:

Perfect Competition

A market structure where many firms sell identical products, entry and exit to the market are easy, and no single firm can influence the market price.

Medium-sized Firms

Companies that occupy the middle ground in terms of annual revenues and employee numbers, larger than small businesses but smaller than large corporations.

Oligopolists

Firms operating in a market structure characterized by a small number of companies that have significant control over market prices and competition.

Monopolistic Competitors

Firms operating in a market structure where many companies sell products that are similar but not identical, allowing for competition on aspects other than just price.