Class Notes (836,147)
Canada (509,656)
Biology (2,437)
BIOLOGY 2B03 (285)
Joe Kim (9)
Lecture 5

Lecture 5.pdf

7 Pages
Unlock Document

Joe Kim

Lecture 5March11121149 AMProtein processing and foldingRERCalled rough because of the studded ribosomes on the membrane giving it a jagged rough lookProtein transport occurs between the RER and Golgi apparatusFunction RER and Golgi apparatus target new proteins to specific destinationssecretory pathwayor cotranslational pathwaySERSynthesis of fatty acids and phospholipidsMetabolism of carbohydratesCalcium concentrationsPosttranslational Modifications and Quality controlModificationModifications are performed so that the correct proteins can go to their correct locations after they have been secreted by the ERGlycosylation covalent addition of carbohydrates1Disulphide bond formation2Folding3Photolytic cleavage4Quality controlUnfolded protein responseGlycosylation of proteinsthe addition of one or more carbohydrate chain to a proteinProteins that are attached to a carbohydrate is called a glycoproteinThe carbohydrates are attached to Ser or Thr or the amide nitrogen on AsnNlinked GlycosylationMost common form of glycosylationAddition of oligosaccharide block to the NHgroup of Asn 14 residues2The oligosaccharide is first assembled onto the dilicholhydrophobic moleculeand then delivered to the protein where it binds to Asparagine AsnThis reaction is catalyzed byoligosaccharyl transferaseMore complex and larger than Olinked Olinked GlycosylationAddition of 14 sugar residues to OH group of Ser ThrFunctions of glycosylationProper foldingTraffickingStabilityCellcell adhesionCell identityDisulfide bridge formationBoth intra and intermolecular disulfide bonds can stabilize tertiary and quaternary structuresOxidative linkage of sulfhydryl groups SHbetween 2 cysteineresiduesIn eukaryotes disulfide bridges can only be formed in the lumen of the ER but in prokaryotes it can be formed both in the lumen and periplasmic space between the outer and inner membrane This means that disulfide bonds are present in only secretory proteinsso the proteins synthesized by free ribosomes must find other ways to stabilize their structureThe ER is an oxidizing environment allowing disulfide bridgesThe Cytoplasm is a reducing environment not allowing disulfide bridgesFormation of disulfide bridgesThe formation of disulfide bridges in the lumen of the ER is depended on the enzyme PDIOxidized PDI reacts with a protein giving the protein its sulfide bond allowing the protein toBIO 2B03 Page 1
More Less

Related notes for BIOLOGY 2B03

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.