Protein Family Models

Superfamily includes proteins containing domains which bind to iron-sulfur clusters. Members include bacterial ferredoxins, various dehydrogenases, and various reductases. Structure of the domain is an alpha-antiparallel beta sandwich. Domain contains two 4Fe4S clusters. (from Pfam)

Date:

2024-08-14

Superfamily includes proteins containing domains which bind to iron-sulfur clusters. Members include bacterial ferredoxins, various dehydrogenases, and various reductases. Structure of the domain is an alpha-antiparallel beta sandwich. Domain contains two 4Fe4S clusters. (from Pfam)

Date:

2024-08-14

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