Rhs repeat-associated core (IPR022385)

Short name: Rhs_assc_core

Overlapping homologous superfamilies


Domain relationships



This entry represents a conserved unique core sequence shared by large numbers of proteins. It is occasionally found in the Archaea, including Methanosarcina barkeri) but commonly found in the bacteria and eukaryotes. Most fall into two large classes. One class consists of long proteins in which two classes of repeats are abundant: an FG-GAP repeat (PF01839) class, and an RHS repeat (PF05593) or YD repeat (TIGR01643). This class includes secreted bacterial insecticidal toxins and intercellular signalling proteins such as the teneurins in animals. The other class consists of uncharacterised proteins shorter than 400 amino acids, where this core domain of about 75 amino acids tends to occur in the N-terminal half. Over twenty such proteins are found in Pseudomonas putida alone; little sequence similarity or repeat structure is found among these proteins outside of this domain.

The C protein of bacterial ABC toxin complexes has a conserved RHS-repeat-containing N-terminal region and a variable C-terminal region, which is the main cytotoxic component. The C protein forms a large hollow shell structure with the B protein encapsulating the divergent C-terminal domain. An explanation for this structure could be that it allows the toxic load to remain sequestered until a change in pH triggers its release. The RHS repeat-associated core domain forms a short strip of beta-sheets that spirals inwards the shell structure, forming a plug at the C end of the shell. The RHS core domain also functions as a self-cleaving protease, cleaving the C-terminal domain from the rest of the protein [PMID: 23913273].

YD repeats are found in many bacterial and eukaryotic proteins, notably in the extracellular domains of teneurin proteins, which are developmental signalling proteins conserved from flies to mammals [PMID: 22841666]. It has been suggested that RHS and YD repeats may represent the same conserved structural motif contributing to a similar shell structure that encapsulates the teneurin C-terminal region [PMID: 23913273].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.