Protein Transport

Chaperones

________ are released as protein is transferred to a channel in the outer membrane.

SRP

________ binds to ER signal sequence and pauses translation.

sequence

Matrix- targeting ________ binds to receptor.

Membrane

________ bound protein translocators directly transport proteins across a(n) ________.

polypeptide

The ________ is completely synthesized and released into the ER lumen.

Protein

________ is completely threaded into the matrix.

Transport of large molecules

________ is active- requires GTP.

Chaperones

________ bind to protein as it enters the matrix.

sequence

Matrix- targeting ________ is cleaved by an enzyme in the matrix.

SRP

________ binds to receptor in ER membrane.

Protein

________ is transferred to a channel in the inner membrane.

Chaperones

________ are released, and protein folds into its three- dimensional structure.

Transport of large molecules is active

requires GTP

Gated transport

Protein traffic between nucleus and cytosol
Nuclear pore acts as a gate

Transmembrane transport

Membrane bound protein translocators directly transport proteins across a membrane
Cytosol 🡪 ER, mitochondria, chloroplast
Transported protein is usually unfolded

Vesicular Transport

Membrane-enclosed transport intermediates
Vary in size
Ferry proteins from one compartment to another

Small molecules (< 60 kDa, or about 9 nm diameter) enter or exit nucleus by

passive diffusion