2. The structure and functions of Endoplasmic Reticulum(Er) (a)Rough endoplasmic reticulum 0.5 um (b)Smooth endoplasmic reticulum 0.5m Figure 12-2 Rough and Smooth Endoplasmic Reticulum studded with ribosomes (TEM).(b)Electron micrograph of smooth la) Electron micrograph of endoplasmic reticulum. The rough ER is endoplasmic reticulum(TEM) RER has ribosomes on the cytosolic side of continuous, flattened sacs(cisternae) SER is an interconnecting network of tubular membrane elements Rough endoplasmic reticulum and Smooth endoplasmic reticulum
2. The structure and functions of Endoplasmic Reticulum(ER) Rough endoplasmic reticulum and Smooth endoplasmic reticulum RER has ribosomes on the cytosolic side of continuous, flattened sacs(cisternae); SER is an interconnecting network of tubular membrane elements
save Figure 8.4 on (step n the vars memb pcs sor konger penods of time (step 3s A m tured oell by lawr Hanning enteral muscus. The ER TR afs Ih renal tratt containing naesowtt-atudded i devoi d nlwsumns) and a cvtreose Miser Microsome(100-200nm) ER of pancreatic cells Microsomes are heterogeneous mixtures of similar-sized vesicles, formed from membranes of the ER and Golgi complex Microsomes retain activity during purification, allowing studies of function and composition
Microsome(100-200nm) rER of pancreatic cells Microsomes are heterogeneous mixtures of similar-sized vesicles, formed from membranes of the ER and Golgi complex. Microsomes retain activity during purification, allowing studies of function and composition
A. Functions of the rER intron d nan aton in te coed o Proteins synthesized on ribosomes of rEr include secretory proteins 若却三 @ em的 integral membrane proteins soluble proteins of organelles rto ER umen oeodBrtNnocrt Figure 2-14 htracelule Sorting of Proein. la) syreestr al pomade acdM by aclw gees trotsinfacymao, The tarp and ani因扩 stansted ww eroj wese海 加aw时 A(magn menteanpoh 们时B的可 hdt升bate口 的m间pph3的as ume)tcl he pshmegto s ous to se commo or frn 试市 ou cosne, orione.alea d加 ppm @f a读 boom ascmnodwb he Eh neaten Mshe memba im pe amen lateral a时 tta tha的 histort nucleus ooen wa te neMr poss am a me n nport thecociatsdeehowtiyetwe a uctt ar mtor nu
A. Functions of the rER ❖ Proteins synthesized on ribosomes of rER include: ➢ secretory proteins, ➢ integral membrane proteins, ➢ soluble proteins of organelles
.o Modification and processing of newly synthesized proteins: glycosylation in the rER The precursor of 14 residues is the same s mannose N-acetyiglucosam in plants, animals crosland single-celled eukaryotes ⊙ polypeptide chain then remove 3 ucoses and 1 mannose in the er told linke N-linked: linked to the amide nitrogen of asparagine (er) O-linked: linked to the hydroxyl group serine or threonine via galNac (in golgi)
❖ Modification and processing of newly synthesized proteins: glycosylation in the rER; N-linked: linked to the amide nitrogen of asparagine (ER) O-linked: linked to the hydroxyl group serine or threonine via GalNac (in Golgi) The precursor of 14 residues is the same in plants, animals, and single-celled eukaryotes then remove 3 glucoses and 1 mannose in the ER
o Quality control of of newly synthesized proteinS---The role of N-linked glycosylation in ER protein folding Proteasome Ribosome The lumen of rEr contains: Unfolded UDP UDP-GIc Bip and calnexin(chaperones) that recognize and bind to unfolded gLucosidase land目 [GT or misfolded proteins and give them 4 Correctly correct con formation folded >Protein disulfide isomerase Glucosidase D Exit(PDI 6 >GT(glucosyl-transferase monitoring enenzyme ) recognize ER lumen unfolded or misfolded proteins and Calnexin mHaTTHT-H mmmmmmm adds a glucose to the end of oligo. Cytosol Quality control: ensuring that misfolded proteins do not leave er
❖ Quality control of of newly synthesized proteins---The role of N-linked glycosylation in ER protein folding Quality control: ensuring that misfolded proteins do not leave ER The lumen of rER contains: ➢Bip and calnexin (chaperones) : that recognize and bind to unfolded or misfolded proteins and give them correct conformation; ➢Protein disulfide isomerase ( PDI ) ; ➢GT(glucosyl-transferase, monitoring enenzyme ) recognize unfolded or misfolded proteins and adds a glucose to the end of oligo