molecule packaging Flashcards
what happens to molecules in the trans Golgi
they are packaged and sorted in the trans golgi network for delivery to specific cellular destinations
how are molecules targeted to lysosomes
targeting is mediated by a mannose 6-phosphage signal, which is added to lysosomal enzymes in the golgi complex during their biosynthesis and processing
which was among the first identified trafficking signals
the mannose 6-phosphate signal requirement
how is delivery of enzymes to lysosomes mediated through endosomes
mannose, hydrolase precursor and p-GlcNAc are joined in cis Golgi network. The M6P signal is uncovered and binds with an M6P receptor in trans Golgi network and is transported in a clathrin coated vesicle to endosome, until it is uncoated. the vesicle fuses with the endosome. The hydrolase precursor and mannose dissociate from the M6P receptor because of acidic pH. the phosphate is removed. The M6P receptor is packaged up in vesicle and sent back to trans golgi network
where are lysosomes formed?
in a pathway that begins with the fusion of endosomes derived from endocytic vesicles and vesicles from the trans golgi network containing lysosomal proteins.
how do endocytic vesicles become early endosomes?
they fuse to form early endosomes, that then transition to late endosomes, then to endolysosomes. upon further maturation, they become lysosomes.
what does endocytic pathway cover?
territory between the plasma membrane, trans golgi network and lysosome.
describe the endocytic pathway to lysosomes?
early endosomes bud off the PM into the cytosol and fuse with vesicles from the TGN that contain lysosomal proteins. endocytic vesicles fuse to form early endosomes that then transition to late endosomes, then to endolysosomes.
what does delivery of lysosomal enzymes use? what does it involve?
the M6P signal and clathrin coats. it can involve the recycling of enzymes and receptors through endosomes, the plasma membrane and TGN.
