Protein-Only Inheritance

Overview

Protein-only inheritance refers to the phenomenon where biological information is transmitted between cells or generations through the self-perpetuating conformation of a protein, rather than through DNA or RNA. This concept is central to the Prion Hypothesis.

Mechanism

The mechanism involves a protein that can exist in at least two stable conformations:

  1. The Native Form: A functional, non-pathological state.
  2. The Prion Form: A self-templating, often aggregated state.

When the prion form comes into contact with the native form, it induces the native form to adopt the prion conformation. This chain reaction allows for the “replication” of the specific protein fold and the transmission of the phenotype (or disease state) associated with that fold.

Non-Pathological Prions

While prions are primarily known for their role in neurodegenerative diseases, protein-only inheritance also occurs in non-pathological contexts, such as:

  • Yeast Prions: Proteins like [Sup35p] can form prions that provide a mechanism for epigenetic inheritance of new traits, allowing for rapid adaptation to environmental stress.
  • Functional Prions in Mammals: Some proteins, such as [CPEB], use prion-like aggregation for the long-term maintenance of synaptic strength and memory.

Scientific Consensus

  • Established Fact: Protein conformation can be transmitted in a self-perpetuating manner (especially in yeast).
  • Hypothesis: This mechanism is the sole driver of mammalian TSEs.
  • Level of Consensus: High (now the mainstream view).