STEPS OF VESICULAR BUDDING AND FUSION (+ PROTEINS INVOLVED)

• Cargo selection (cargo receptor, adaptor protein)
• Vesicular budding (adaptor proteins, coat proteins)
• Fission from donor membrane (dynamin)
• Vesicular coat dissociates
• Vesicular targeting and transport (Rab-GTPase, tethering protein)
• Fusion with target membrane (V-snare and T-snare)

PROTEINS OF VESICULAR BUDDING AND FUSION

• Cargo receptors – select and concentrate molecules to be transported in vesicle
• Adaptor proteins – bind cargo receptor and coat proteins
• Coat proteins – form protein scaffold around vesicle that facilitate facilitate vesicular budding
• Dynamin – GTPase involved in vesicular fission
• RabGTPase – associates with vesicle after coat has dissociated. Facilitates transport of vesicle to appropriate target membrane. Locks vesicle to target membrane by attaching tethering proteins
• Tethering proteins – anchored in target membrane, attach rabGTPase. Move vesicle close to target membrane for vesicular fusion.
• V-snares(vesicular) and T-snares(target membrane) – Play role in vesicular fusion

COAT PROTEINS DIRECT VESICLE TRANSPORT

• Clathrin +adaptin 1: Golgi → Lysosome
• Clathrin + adaptin 2: Plasma membrane → Endosomes (endocytosis)
• COP 1: Cis golgi → ER AND Later cisternae → Earlier ones (retrograde transport)
• COP II: ER → Cis golgi