Protein Family Models

This family is most frequently associated with a Fer4 iron-sulfur cluster towards the C-terminal region. (from Pfam)

Date:

2025-01-31

Many proteins that fold in the cytosol because a required cofactor is available there only, or because cytosolic chaperones assist in folding, or because high salt in the extracellular milieu would interfere with folding there, cannot rely on the standard general secretory (Sec) pathway for secretion across the plasma membrane. This model describes a family of predicted long, non-Sec signal sequences and signal-anchor sequences (uncleaved signal sequences). All contain a typically invariant pair of arginine residues, in a motif approximated by (S/T)-R-R-X-F-L-K, followed by a membrane-spanning hydrophobic region. The system that secretes pre-folded proteins with this motif is known as twin-arginine translocation, or TAT. Note that some variant forms, often lineage-specific ones such as the RKxFL version found in Leptospira, do occur but typically fall outside the scope of this HMM. Twin-arginine signal domains with small amino acid side chains at the -1 and -3 positions from the C-terminus of the model should be predicted to be cleaved as are Sec pathway signal sequences. The system, although far from universal in prokaryotes, is widespread in bacteria and present also in many archaea.

Date:

2019-11-27

This model represents a family of corrin and 8-iron Fe-S cluster-containing reductive dehalogenases [1] found primarily in halorespiring microorganisms such as dehalococcoides ethenogenes which contains as many as 17 enzymes of this type with varying substrate ranges. One example of a characterized species is the tetrachloroethene reductive dehalogenase [2] (1.97.1.8) which also acts on trichloroethene converting it to dichloroethene.

Date:

2019-09-10