SUPERFAMILY 1.75 HMM library and genome assignments server

SUPERFAMILY 2 can be accessed from supfam.org. Please contact us if you experience any problems.

  Home > SCOP hierarchy > Mitochondrial import receptor subunit Tom20 superfamily


Mitochondrial import receptor subunit Tom20 superfamily

SCOP classification
Root:   SCOP hierarchy in SUPERFAMILY [ 0] (11)
Class:   All alpha proteins [ 46456] (284)
Fold:   Open three-helical up-and-down bundle [ 47143] (7)
Superfamily:   Mitochondrial import receptor subunit Tom20 [ 47157]
Families:   Mitochondrial import receptor subunit Tom20 [ 47158]

 Superfamily statistics
Genomes (358) Uniprot 2018_03 genome PDB chains (SCOP 1.75)
Domains 475 1,428 1
Proteins 472 1,418 1

 Functional annotation
General category Processes_IC
Detailed category Transport

Document: Function annotation of SCOP domain superfamilies

InterPro annotation
Cross references IPR002056 SSF47157 Protein matches
Abstract Virtually all mitochondrial precursors are imported via the same mechanism [PubMed7709435]: precursors first bind to receptors on the mitochondrial surface, then insert into the translocation channel in the outer membrane. Many outer-membrane proteins participate in the early stages of import, four of which (MAS20, MAS22, MAS37 and MAS70) are components of the receptor. MAS20, which forms a subcomplex with MAS22, seems to interact with most or all mitochondrial precursors, suggesting that the protein binds directly to mitochondrial targeting sequences. The MAS37 and MAS70 components also form a subcomplex, the two subcomplexes possibly binding via their trans- membrane (TM) regions - the TM region of MAS70 promotes oligomerisation of attatched protein domains and shares sequence similarity with the TM region of MAS20 [PubMed8163528].

InterPro database

PDBeMotif information about ligands, sequence and structure motifs
Cross references PDB entries
Ligand binding statistics
Nucleic-acid binding statistics
Occurrence of secondary structure elements
Occurrence of small 3D structural motifs

PDBeMotif resource

Jump to [ Top of page · SCOP classification · InterPro annotation · PDBeMotif links · Functional annotation ]

Internal database links

Browse genome assignments for this superfamily. The SUPERFAMILY hidden Markov model library has been used to carry out SCOP domain assignments to all genomes at the superfamily level.

Alignments of sequences to 1 models in this superfamily are available by clicking on the 'Alignments' icon above. PDB sequences less than 40% identical are shown by default, but any other sequence(s) may be aligned. Select PDB sequences, genome sequences, or paste in or upload your own sequences.


Browse and view proteins in genomes which have different domain combinations including a Mitochondrial import receptor subunit Tom20 domain.

Examine the distribution of domain superfamilies, or families, across the major taxonomic kingdoms or genomes within a kingdom. This gives an immediate impression of how superfamilies, or families, are restricted to certain kingdoms of life.


Explore domain occurrence network where nodes represent genomes and edges are domain architectures (shared between genomes) containing the superfamily of interest.

There are 1 hidden Markov models representing the Mitochondrial import receptor subunit Tom20 superfamily. Information on how the models are built, and plots showing hydrophobicity, match emmission probabilities and insertion/deletion probabilities can be inspected.


Jump to [ Top of page · SCOP classification · InterPro annotation · PDBeMotif links · Functional annotation · Internal database links ]
Please cite: Gough, J., Karplus, K., Hughey, R. and Chothia, C. (2001). "Assignment of Homology to Genome Sequences using a Library of Hidden Markov Models that Represent all Proteins of Known Structure." J. Mol. Biol., 313(4), 903-919.

Please send feedback, comments or questions to superfamily@cs.bris.ac.uk or use the feedback form.

© Copyright 2013 The SUPERFAMILY authors and Julian Gough.