ER +secretory Pathway Flashcards
Describe the structure of endoplasmic reticulum?
It’s continuous with nuclear envelope
2 bilayers=> inner + outer nuclear membrane
What is perinuclear space?
Space between 2 membranes of ER
What is nuclear lamina and what is its function?
Network of proteins that lines inside of nuclear envelope
It maintains the structure of nucleus
Nuclear lamina proteins are often involved in gene regulation + regulation of gene expression
What is function of ER?
Protein synthesis, glycosylation, folding + assembly + multi protein synthesis
Lipid synthesis
Ca2+ sequestration
Detoxification by cytochrome p450 enzymes
Co-translational protein targeting to ER
Key words
Signal sequence= guide ribosome complex to surface of ER SRP (signal recognition particle) SRP receptor where SRP complex binds Translocation complex Signal peptidase
What are protein modifications?
Proteolysis (signal peptide)
Disulphide bond formation
Glycolysation => attachment of sugar molecules
Deglycolysation=> sugar molecules are removed
Protein folding + assembly (tertiary, quaternary structure)
What is secretory pathway?
Transport of proteins from one organelle to another always occur via vesicular transport
Proteins packaged into vesicles that membrane bound
Vesicles move to cytoplasm + fuse with target bilayer + contents are released into target membrane
What is ER quality control?
Proteins that fail any one quality check I.e. proteolysis, glycolysation, disulphide bond formation, folding, assembly into complex will not be exported from ER + are degraded instead
Describe structure of Golgi apparatus?
Series of different membrane stacks
2 different domains of Golgi-> cis side +trans side=> side that faces the ER where vesicles come that carry proteins called Cis side, where vesicles leave to transport proteins onto other places of cell called trans side of Golgi apparatus
Flattened vesicles in middle (cisterna) is called medial Golgi=> is where most of enzymes that carry lipid + protein modification is located
What is role of Golgi apparatus?
Protein modification : -glycosidases, glycosyltransferase - O-linked glycolysation - sulfatases -proteases Lipid synthesis Protein + lipid sorting to: -Secretory granules -Plasma membrane -Endosomes -Lysosomes
What is cis face + trans face in Golgi apparatus?
Cis face is receiving department
Trans face is shipping department
