The small Tim proteins and the twin Cx3C motif.
The mitochondrial intermembrane space contains the 'small' Tim (translocase of inner membrane) proteins that are marked by their conserved 'twin Cx(3)C' motif separated by 11-16 residues. Together with the Tim22 complex at the inner membrane, the small Tim proteins form the TIM22 import machinery that mediates the biogenesis of polytopic inner membrane proteins. Upon first investigation, the conserved motif resembles a zinc-finger-like domain, but the spacing between the cysteine residues differs from that a canonical zinc finger. Recent publications present different views about the function of the conserved cysteines: the cysteines form a zinc-finger-like structure to coordinate zinc or, alternatively, they form juxtapositioned disulfide bonds.
Koehler
Carla M
CM
Department of Chemistry and Biochemistry and Molecular Biology Institute, UCLA, Los Angeles, CA 90095, USA. koehler@chem.ucla.edu
D020816:Amino Acid Motifs; D000818:Animals; D018797:Cell Cycle Proteins; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000378:metabolism*; D014157:Transcription Factors; D015032:Zinc / Q000737:chemistry / Q000378:metabolism
D018797:Cell Cycle Proteins; D004220:Disulfides; D047908:Intracellular Signaling Peptides and Proteins; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; C509769:TIMELESS protein, human; C509770:Timeless protein, mouse; D014157:Transcription Factors; D015032:Zinc; D003545:Cysteine