SUPERFAMILY 1.73 HMM library and genome assignments server


Anti-sigma factor antagonist SpoIIaa superfamily

SCOP classification
Root:   SCOP hierarchy in SUPERFAMILY [ 0] (11)
Class:   Alpha and beta proteins (a/b) [ 51349] (141)
  Mainly parallel beta sheets (beta-alpha-beta units)
Fold:   SpoIIaa-like [ 52086] (2)
  core: 4 turns of a (beta-alpha)n superhelix
Superfamily:   Anti-sigma factor antagonist SpoIIaa [ 52091]
Families:   Anti-sigma factor antagonist SpoIIaa [ 52092]


Superfamily statistics
Genomes (968) UniProt 15.0 PDB chains (SCOP 1.73)
Domains 4,621 4,807 6
Proteins 4,615 4,798 6


Functional annotation
General category Other
Detailed category Unknown function

Function annotation of SCOP domain superfamilies
InterPro annotation
Cross references IPR002645 SSF52091 Protein matches
Abstract The STAS (Sulphate Transporter and AntiSigma factor antagonist) domain is found in the C-terminal region of sulphate transporters and bacterial anti-sigma factor antagonists. It has been suggested that this domain may have a general NTP binding function. The establishment of differential gene expression in sporulating Bacillus subtilis involves four protein components one of which is SpoIIAA . The four components regulate the sporulation sigma factor F. Early in sporulation, SpoIIAA is in the phosphorylated state (SpoIIAA-P), as a result of the activity of the ATP-dependent protein kinase SpoIIAB . The site at which this protein is a conserved serine. SpoIIAB is an anti-sigma factor that in its free form inhibits F by binding to it. Competition by SpoIIAA (the anti-anti-sigma factor) for binding to SpoIIAB releases Sigma F activity [PubMed9560229]. The STAS domain is found in the anti-sigma factor antagonist SpoIIAA.

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

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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 4 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 Anti-sigma factor antagonist SpoIIaa 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 4 hidden Markov models representing the Anti-sigma factor antagonist SpoIIaa 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 ]