Wordlists for Exam 2
Lectures 20 & 21 - Cytoplasmic Protein Targeting

Targeting signal sequences (aka Targeting Sequence)
Mitochondrial matrix targeting - Cleaved N-terminal signal sequence

cationic (basic) amino acids every 3rd or 4th position
some hydrophobic amino acids
some -OH containing amino acids (serine & threonine)
no acidic amino acids
amphipathic alpha-helix with positively charged edge


Chloroplast stroma targeting - Cleaved N-terminal uncharged amphipathic alpha-helix

25-35% -OH containing amino acids (serine & threnine)
rich in small hydrophobic amino acids

matrix/stroma hsp 60 chaperonins that may assist folding
membrane contact site
TOM = Translocase of the Outer Mitochondrial membrane complex
TIM = Translocase of the Inner Mitochondrial membrane complex
TOC = Translocase of the Outer Chloroplast membrane complex
TIC = Translocase of the Inner Chloroplast membrane complex
TIM 23
TIM 22
OXA
PAM (Presequence Associated Translocation Motor)

NLS

karyopherins
nuclear import receptor proteins - bind NLS
nuclear export receptor proteins - bind nuclear export signal


Ran GTPase cycle

GAP - GTPase Activating Protein
GEF - Guanine Nucleotide Exchange Factor


Peroxisome matrix protein targeting sequences

C terminal sequence (SKL = serine-lysine-leucine) - PTS-1 = Pex 5

receptor = PTS1 R (Protein Targeting Sequence 1 Receptor)
N-terminal sequence (11-37 amino acids long) - PTS-2 = Pex 7

receptor = PTS2 R (Protein Targeting Sequence 2 Receptor)

peroxin
Zellweger Syndrome - peroxisomes form, but enzymes not imported into matrix
PMP70 (70 kd Peroxisomal Membrane Protein)
Pex 1
Pex 3
Pex 2, Pex 16
Thiolase
Pex 13

End of Material for Exam 2

Return to Cell Biology Homepage