Suppressorproteiner

Suppressorproteiner, or suppressor proteins, are proteins that counteract the effect of a mutation or adverse cellular state, thereby suppressing an abnormal phenotype. They are typically encoded by suppressor genes and can act at different levels of cellular function. In genetics, suppressor proteins may fall into two broad classes: intragenic suppressors, whose products reside in the same gene affected by the mutation, and extragenic suppressors, which act from a different gene. The mechanisms include restoring the activity of a mutated protein, altering gene expression to bypass the defect, or modifying a biochemical pathway so that the phenotype is masked rather than corrected at the causal mutation.

In cell signaling and regulation, suppressor proteins function as negative regulators that dampen pathways to prevent overactivation. An example is the SOCS (suppressor of cytokine signaling) protein family, which inhibits JAK-STAT signaling by binding to JAK kinases or receptors and promoting their degradation. Protein phosphatases and certain ubiquitin ligases also act as suppressors by removing phosphate groups or targeting components for degradation, respectively.

Clinical relevance: loss or gain of suppressor protein activity can contribute to disease, including immune dysregulation and cancer. In research, suppressor proteins help illuminate genetic networks through suppressor-by-phenotype approaches and are explored as therapeutic targets to modulate signaling pathways.

See also: suppressor gene, SOCS proteins, gene regulation.