Pro-opiomelanocortin (POMC) undergoes tissue specific prohormone convertase cleavage. In the human adult anterior pituitary corticotroph, which product set results?

• A Beta-endorphin exclusively, because corticotrophs express only PC2
• B Alpha-MSH, corticotropin-like intermediate peptide and CLIP as major products
• C ACTH alone, with all other fragments degraded intracellularly
• D ACTH, beta-lipotropin and beta-endorphin, but no separately secreted melanocyte stimulating hormone ✓

Explanation

In the anterior lobe, prohormone convertase 1 cleaves POMC into ACTH and beta-lipotropin, with beta-endorphin further derived from beta-LPH. Although ACTH contains the alpha-MSH sequence within it, humans lack a functional intermediate lobe, so no separately secreted MSH product forms. Option B describes the rodent intermediate lobe pattern produced by PC2 cleavage, which does not apply to the adult human anterior pituitary.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.