Questions: In addition to the anti-VEGF antibody, a VEGFR primary antibody was also added. At which position do you expect the band for VEGFR to appear? Remember that in SDS-PAGE, proteins are separated according to their molecular weight. a) VEGFR runs at a lower molecular weight than VEGF b) VEGF and VEGFR run at the same molecular weight c) VEGFR runs at a higher molecular weight than VEGF d) VEGFR cannot be detected by Western blotting

The answer is c) VEGFR runs at a higher molecular weight than VEGF.

Explanation for each option:

a) VEGFR runs at a lower molecular weight than VEGF: This is incorrect. VEGFR (Vascular Endothelial Growth Factor Receptor) is a receptor protein that is typically larger than its ligand, VEGF (Vascular Endothelial Growth Factor). Receptors generally have a higher molecular weight due to their more complex structure and additional domains required for signal transduction.

b) VEGF and VEGFR run at the same molecular weight: This is incorrect. VEGF and VEGFR are different proteins with different structures and functions, leading to different molecular weights. VEGFR, being a receptor, is larger than VEGF.

c) VEGFR runs at a higher molecular weight than VEGF: This is correct. VEGFR is a receptor protein that is larger and more complex than VEGF, which is a smaller signaling molecule. Therefore, in SDS-PAGE, VEGFR would appear at a higher molecular weight position compared to VEGF.

d) VEGFR cannot be detected by Western blotting: This is incorrect. VEGFR can be detected by Western blotting if the appropriate primary and secondary antibodies are used. The question specifies that a VEGFR primary antibody was added, indicating that detection is intended and possible.

In summary, VEGFR, being a receptor, is expected to have a higher molecular weight than VEGF, and thus would appear at a higher position on an SDS-PAGE gel.