Amyloid-Forming peptide GNNQQNY, a biologically active heptapeptide derived from the N-terminal prion-determining domain of yeast Sup35, is instrumental in amyloid fibril formation. Its atomic oligomeric structure has been detailed, serving as an excellent model for investigating early-stage aggregation. The peptide can form three stable β-sheet structures: in-register parallel, off-register parallel, and anti-parallel. Notably, the in-register parallel dimer aligns closely with amyloid β-sheet architecture, relying on fewer interpeptide hydrogen bonds and emphasizing hydrophobic interactions, which enhances conformational entropy relative to the anti-parallel arrangement.