Even if you didn't know anything about the gene mentioned they tell you the PROTEIN serves as a precursor for making the hormones thus it has already undergone translation and the only choice that makes sense is Post-translational modification. Additionally, mRNA means it has already undergone splicing and post-transcriptional modification as it would be called hnRNA otherwise. (FA2020 pg 41)

POMC is a prohormone peptide chain.

It is translated and later enzymes cut this peptide in the subpeptides.

Transcription is wrong (i had this too...) b/c its not the mRNA that makes different peptide hormones. Moreover, what I see now is, that posttranscriptional modification is more or less splicing... so post-translat. modification. next time we make it correct ;-)

Keywords from Dr. Turco from Kaplan:

• Replication- DNA
• Transcription- RNA
• Translation- Protein

POMC is a prohormone peptide chain that gets cleaved into gamma-MSH, ACTH, gamma-lipotropin, and beta-endorphin. There's a nice figure of this in Costanzo (Fig 9-10).

It may help to remember that pathologies with increased ACTH (ie Addison's disease) can present with hyperpigmentation since MSH (melanocyte stimulating hormone) is produced alongside ACTH.

It's saying a particular protein is made from this mrna, this protein is used as a precursor to produce those two hormones. so proteins once made, they need post translational trimming of N and C propeptides to be active. like trypsinogen becomes trypsin else they are just inactive protein. So any protein to work they need to go through post translational modifications.

I was also torn between alternative splicing and post-translational modification but this is how I reasoned towards post-translational modification:

In primary adrenal insufficiency (Addison disease), you have increased ACTH production from POMC. And these individuals also get increased melanin synthesis because of MSH. Basically, you can't make ACTH without making the other stuff. In alternative splicing, you make only ONE product because you cut out the exons of the genes you don't want! A little long-winded but hope this help tie in the concept. Source: FA 2019 Pg 334

Fun fact: JFK had this disease.

So if a long polypeptide string is generated from signle mRNA then cleaved → post-translational modification.

If modification happens at level of RNA which is cleaved into smaller mRNA that then give proteins → alternative splicing / post-tranSCRIPTIONAL modification.