Multiple sorting pathways between the late Golgi and the vacuole in yeast

Area of Science:

• Cell Biology
• Molecular Biology
• Protein Trafficking

Background:

• Proteins synthesized in the Golgi are sorted to various destinations, including the cell surface and vacuole.
• Two primary routes, the CPY pathway and the ALP pathway, mediate Golgi-to-vacuole transport.
• The CPY pathway involves transit through an endosomal/prevacuolar compartment (PVC), while the ALP pathway bypasses the PVC.

Purpose of the Study:

• To investigate the distinct mechanisms and regulatory proteins involved in Golgi-to-vacuole protein sorting.
• To identify signals and protein factors that direct proteins to either the CPY or ALP pathway.
• To elucidate the molecular machinery, including SNARE complexes, governing vacuolar transport.

Main Methods:

• Analysis of protein sorting pathways using genetic and molecular approaches.
• Identification of genes regulating CPY and ALP pathway specificity.
• Characterization of SNARE complexes involved in transport to the PVC and vacuole.

Main Results:

• The ALP pathway is signal-mediated and saturable, distinct from the CPY pathway.
• Specific genes have been identified for each pathway, with others affecting both.
• Progress made in identifying SNARE proteins crucial for Golgi-to-PVC and vacuole fusion.

Conclusions:

• At least two distinct pathways (CPY and ALP) exist for Golgi-to-vacuole protein transport.
• Regulation of vacuolar targeting involves pathway-specific and common factors.
• SNARE complexes play critical roles in mediating vesicle fusion events during vacuolar transport.