Exocytosis Flashcards
what is exocytosis?
molecules released from cell
what are the two forms of exocytosis?
constitutive and regulated
what is constitutive exocytosis?
in all cells all the time, unregulated
inserting new membrane protens and releasing some soluble substances and ecm components
what is regulated exocytosis?
fusion of vesicle to membrane after stimulus
hormone release
what regulate the calcium triggers involved in exocytosis?
SNARE proteins
what are SNARE proteins?
soluble NSF attachment protein receptor proteins
accessory but not unnecessary
how do SNARE proteins work in exocytosis?
snare motifs entangle to pull vesicle into contact with membrane
snare motifs are helixal and all snares have 4 motifs
expose zero layer to make complex fall apart
what three snare motifs are essential for regulated exocytosis?
VAMP
SNAP25
Syntaxin
these are snare motifs
what are two accessory protiens in exocytosis that breakup the SNARE complex and how?
alpha-snap and NSF
work by accessing zero layer
what is synaptotagmin?
calcium sensor
how vesicle knows it needs to be diffusing with membrane
what is MUNC-18?
interacts with syntaxin to act like a clamp
represses snare motif
munc 18 is an inhibitor
what is synaptotagmin-1?
calcium sensor for regulated exocytosis
essential to membrane fusion
