Cell Bio Lecture 16

Front 1

How do proteins localize to where they are needed?

Back 1

-the signal corresponds to a receptor protein associated with an organell that allows it entry
-entry across a membrane is often performed by a translocation channel protein
-typically requires energy
-signal is usually 20-50 AA long

Front 2

TOM and TIM

Back 2

-Translocon of outer membrane
-Translocon of inner membrane

-opening in mitochondrial matrix for bringing in protein
-align via diffusion; must meet to transport protein into matrix

Front 3

Precursor protein

Back 3

-made in cytoplasm, not folded
-attaches to chaperon protein (HSC70 for mitochondria) for transport

Front 4

HSC70

Back 4

-chaperon protein, keeps precursor protein (for mitochondria) unfolded, uses ATP
-pulls protein inside mitochondria, uses ATP; protein later folded by another chaperon protein

Front 5

Chloroplasts have how many membranes to penetrate to bring in a protein?

Back 5

3 membranes/proteins

Front 6

Receptor protein on mitochondrial matrix

Back 6

Directly adjacent to TOM, attaches to signal sequence to bring protein into matrix

Front 7

Endoplasmic reticulum and proteins

Back 7

-proteins imported and created in ER (mostly created)
-starting place of proteins destined for golgi and the rest of the cell

Front 8

ER: water-soluble proteins

Back 8

pass into lumen of ER and will be moved into vesicles

Front 9

ER: transmembrane proteins

Back 9

either stay in ER, go to golgi via vesicles, go to cell plasma membrane, or to other parts of the cell (other membranes)

Front 10

Ribosomes

Back 10

large and small subunits are recycled
-mRNA encoding a cytosolic protein remains free in cytosol-->builds into polyribosome free in cytosol (polypeptide chain is built)
-16-30 hydrophobic AA residues at N-terminus directs the ribosome complex to the ER

Front 11

Polyribosomes

Back 11

-ribosomes bind to mRNA, make a new copy of proteins
-polypeptide chains protrude out

Front 12

Ribosomes - recycled subunits

Back 12

Front 13

mitochondrial matrix localization image

Back 13

Front 14

mitochondrial matrix localization image

Back 14

Front 15

signal peptidase

Back 15

cleaves signal sequence from protein

Front 16

contact site

Back 16

area where TIM and TOM align

Front 17

matrix targeting sequence

Back 17

signal sequence specific for mitochondrial matrix