Pg. 367

Membrane Protein Movement

Single Protein

Tethered tocytoskeleton

Tethered to otherMembrane proteins

Pg. 385

CytosolNucleusMitochondriaChloroplasts

ERGolgiEndosomeLysosomeTransmembraneSecreted

CytosolNucleusMitochondriaChloroplasts

ERGolgiEndosomeLysosomeTransmembraneSecreted

The Nucleus

Nuclear Structure

Nuclear Lamina

Nuclear Structure

Nuclear Pore Complex

Table 15-1 (page 504)

Nuclear Localization Signal (NLS)

Protein Transport to the Nucleus

-Pro-Pro-Lys-Lys-Lys-Arg-Lys-Val-N C

Pg. 504

NLS is Necessary for Nuclear Import

Nuclear Protein withNLS

NLS

Nucleus Nucleus

Nuclear protein withNLS removed

NLS removedfrom protein

Pg. 504

NLS is Sufficient for Nuclear Import

Nucleus Nucleus

Nuclear protein withNLS removed

NLS removedfrom protein

Cytosolic ProteinWithout NLS

Cytosolic ProteinWith NLS

Nuclear Import Pathway

Pg. 541

Regulated Nuclear Import

Pg. 542

Allostery!NLS “masked”

NLS “exposed”

CytosolNucleusMitochondriaChloroplasts

ERGolgiEndosomeLysosomeTransmembraneSecreted

Table 15-1 (page 504)

ER Import Sequence

Hydrolysis of thispeptide bond bySignal Peptidase enzyme

N-Met-Met-Ser-Phe-Val-Ser-Leu-Leu-Leu-Val-Gly-Ile-Ile-Phe-Trp-Ala-Thr- C

RecognitionSequence

N

N

NNN

N

C

CCC

C

Membrane “budding”

Clathrin “triskelion”

Clathrin “Cage”

Dynamin GTP Hydrolysis

N

NNNN

C

CCC C

Vesicle Fusion with Membrane

v-SNARE/t-SNARE Interaction

Membrane fusion step is regulatedSecretory

vesicle

Outside of cell

Cytosol

Ca++

Clostridium botulinum

Botulism Toxin

Protease

Botulism Toxin (tan)

t-SNARE (green)

Botulism Toxin

Botulism Toxin Protease

Botulism Toxin