Biology Passage

[1mcataway]

Spring, a secreted protein, is produced as a precursor form called prospring. The maturation of spring requires that a short N-terminal segment be cleaved.
There is two sets of antibodies that are generated called Pro and C-spring. Pro binds to the short peptide that is cleaved from spring during the maturation process. C-spring binds the C-terminal half of spring.
These antibodies are used to determine where within the secretory pathway propeptide cleavage occurs. 3 different cellular fractions are collected: ER, cis-Golgi, and trans-Golgi.
However, the labels have come off of the test tubes containing each of the cellular fractions. But the experiment is continued. In addition to the anti-spring antibodies, astutely the fractions are probed with antibodies to clathrin and COP-II proteins.

Results are summarized in the following Table attached.

The questions are

Fractions 1, 2, 3 contains which one in the given order?
A- cis-Golgi, ER, trans-Golgi
B- ER, cis-Golgi, trans-Golgi
C- cis-Golgi, trans-Golgi, ER
D-trans-Golgi, ER, cis-Golgi

In which fraction is the spring protein likely to be processed into its mature form?
A-Fraction 1
B-Fraction 2
C-Fraction 3
D-None

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[TieuBachHo]

I can't open the attachment. Are you sure it's a correct file type (extension)? Is it a TABLE.doc or TABLE.docx?

 

[unique135]

I doubt this is for MCAT. I didn't knew what COPII protein was.


C-Spring (main protein) should be present in all.
Pro should be cleaved into cytoplasm. However, here, it is cleaving in the trans-Golgi. Since the protein is secreted, pro is cleaved and prepared on the trans.
COPII proteins are on the vesicles that transport proteins from ER to cis-Golgi.
Clarithin proteins are on the vesicles that transport proteins from trans-Golgi to cystoplasm or membrane.

Fraction 1: trans-Golgi
Fraction 2: ER
Fraction 3: cis-Golgi

Fractions 1, 2, 3 contains which one in the given order?
A- cis-Golgi, ER, trans-Golgi
B- ER, cis-Golgi, trans-Golgi
C- cis-Golgi, trans-Golgi, ER
D-trans-Golgi, ER, cis-Golgi


In which fraction is the spring protein likely to be processed into its mature form?
A-Fraction 1
B-Fraction 2
C-Fraction 3
D-None