Protein-Protein Interactions

Yeast Two-Hybrid (YTH) System for Mapping Protein Interactions

Advantage:
The YTH system

detects weak or transient protein interactions in vivo,

which may be missed by biochemical methods (e.g., co-IP).

By reconstituting a functional transcription factor through bait-prey binding,

it amplifies signals via reporter gene activation (e.g., HIS3, lacZ),

enabling identification of interactions with low affinity.

east Two-Hybrid (YTH) System for Mapping Protein Interactions

Limitation:

system is prone to false positives

due to non-specific interactions or auto-activation of reporter genes by bait proteins alone.

interactions requiring post-translational modifications (e.g., phosphorylation) or proper cellular localization (e.g., membrane proteins) may not occur in the yeast nucleus,

limiting its applicability.

Protein Interaction "Hubs" in Biological Networks

Biological Function:
Protein hubs are

highly connected nodes in interaction networks

Protein Interaction "Hubs" in Biological Networks

Biological Function:
Protein hubs are highly connected nodes in interaction networks, often serving as:

1. Integrators

   1. Essential genes:

1. Integrators of cellular processes

1. (e.g., signaling cascades or transcriptional regulation).

1. Essential genes:

1. Knockouts frequently lead to lethality or severe phenotypes due to their central role (e.g., p53 in stress responses).

Protein Interaction "Hubs" in Biological Networks

Disease Relevance:

1. Mutation Vulnerability:

   1. Drug Targets:

1. Mutation Vulnerability: .

1. Hub proteins are enriched for disease-associated mutations (e.g., cancer-linked hubs like BRCA1)

1. Drug Targets:

1. Their centrality makes hubs attractive for therapeutic intervention (e.g., kinase inhibitors in cancer).