Isolation and characterization of SRF accessory proteins

Area of Science:

• Molecular Biology
• Gene Regulation
• Signal Transduction

Background:

• Growth factor-regulated genes often share a common regulatory element known as the serum response element (SRE).
• SRE activation involves a ternary complex of serum response factor (SRF) and a p62/TCF protein.
• Understanding the components of this complex is key to deciphering gene regulation pathways.

Purpose of the Study:

• To identify proteins with p62/TCF DNA binding properties using a yeast genetic screen.
• To characterize the novel protein SAP-1 and its relationship to other SRF accessory proteins.
• To investigate the functional domains of SAP-1 and their role in ternary complex formation and MAP kinase regulation.

Main Methods:

• Yeast genetic screening to isolate cDNAs encoding proteins with specific DNA binding capabilities.
• Sequence analysis to identify homologous regions between novel proteins and known factors.
• Functional domain analysis to determine the role of specific protein regions in complex formation.

Main Results:

• A yeast genetic screen successfully isolated cDNAs encoding SAP-1, a protein exhibiting p62/TCF DNA binding properties.
• SAP-1 shares homology with Elk-1, another SRF accessory protein, with conserved regions involved in SRF interaction.
• A distinct region in SAP-1 contains conserved MAP kinase phosphorylation sites, suggesting a role in signal transduction.

Conclusions:

• SAP-1 is a novel SRF accessory protein involved in regulating gene transcription through the SRE.
• The identified domains of SAP-1 are critical for its cooperative interaction with SRF in ternary complex formation.
• The presence of MAP kinase sites suggests SAP-1 integrates growth factor signaling pathways into transcriptional regulation, potentially impacting genes like c-fos.