Signal recognition particle-dependent secretome in humans.

Area of Science:

• Cell Biology
• Proteomics
• Molecular Mechanisms

Background:

• Secreted and membrane proteins constitute approximately 30% of the cellular proteome.
• Protein transport occurs via signal recognition particle (SRP)-dependent or independent pathways.
• The specific roles of these pathways in mammals remain largely uncharacterized.

Purpose of the Study:

• To differentiate between SRP-dependent and SRP-independent proteins in mammalian cells.
• To investigate the impact of SRP deficiency on protein abundance and cellular pathways.
• To identify novel proteins and regulatory networks involved in protein secretion and quality control.

Main Methods:

• Mass spectrometry was employed to analyze protein abundance in cells and conditioned medium.
• Experiments were conducted under conditions of defective signal recognition particle (SRP) function.
• Bioinformatic analysis was used to identify protein networks and compensatory pathways.

Main Results:

• A significant decrease in the abundance of many secreted and cellular proteins was observed upon SRP defect, confirming SRP dependence for the human secretome.
• Novel SRP-independent proteins were identified.
• Potential compensatory pathways and a protein network involved in the quality control of secretory/membrane proteins and their mRNAs were discovered.

Conclusions:

• The majority of the human secretome is dependent on signal recognition particle (SRP) pathways.
• SRP deficiency impacts protein abundance and triggers compensatory mechanisms.
• New insights into the regulation of protein secretion and quality control in mammalian cells were gained.