Question

G Protein Kinase A is a family of enzymes whose activity is dependent on cellular levels of cyclic AMP. A PKA sample on an SDS-PAGE gel shows two protein bands. What could this indicate?

A) Post-translational modifications
B) Different isoforms of PKA
C) Protein degradation
D) Sample contamination

Answer 1

Two bands on an SDS-PAGE gel of a Protein Kinase A sample could indicate different isoforms, post-translational modifications, protein degradation, or sample contamination, all affecting the protein's migration through the gel.

Step-by-step explanation:

If a PKA sample on an SDS-PAGE gel shows two protein bands, this could indicate several possibilities:

• Different isoforms of PKA, meaning slightly different versions of the same enzyme that might have variations in amino acid sequences.
• Post-translational modifications such as phosphorylation, which could alter the mobility of the protein on the gel.
• Protein degradation products, which means the protein may have been partially broken down into smaller fragments.

Given that Protein Kinase A (PKA) is a cyclic AMP-dependent kinase, it plays a crucial role in G-protein mediated signal transduction, where it's responsible for phosphorylating target proteins. Therefore, observing two bands might represent different functional states of the enzyme due to one of the mentioned scenarios.