This motif occurs C-terminal to leucine-rich repeats in "sds22-like" and "typical" LRR-containing proteins. Examples from the metazoa are described as either "Acidic leucine-rich nuclear phosphoprotein 32 family member A" or have been characterised as U2A', the protein that interacts with U2B'' facilitating the interaction with U2 snRNA. U2A' is required for the spliceosome assembly and the efficient addition of U2 snRNP onto the pre-mRNA [ (PUBMED:9799242) ]. The crystal structure of the spliceosomal U2B"-U2A' protein complex bound to a fragment of U2 small nuclear RNA has been described [ (PUBMED:9716128) ].
Family alignment:
There are 9616 LRRcap domains in 8937 proteins in SMART's nrdb database.
Click on the following links for more information.
Evolution (species in which this domain is found)
Taxonomic distribution of proteins containing LRRcap domain.
This tree includes only several representative species. The complete taxonomic breakdown of all proteins with LRRcap domain is also avaliable.
Click on the protein counts, or double click on taxonomic names to display all proteins containing LRRcap domain in the selected taxonomic class.
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
A capping domain for LRR protein interaction modules.
FEBS Lett. 1999; 456: 349-51
Display abstract
Leucine-rich repeats (LRR) are protein interaction modules which are present in a large number of proteins with diverse functions. We describe here a novel motif (16-19 residues) downstream of the last, incomplete, LRR in a subfamily of LRR proteins. In the U2A' spliceosomal protein, this motif is folded into a cap that shields the hydrophobic core of the LRRs from the solvent. Modelling of the LRR-cap in the imidazoline-1 candidate receptor, using the known structure of U2A' as template, showed a conservation of the basic structural features.
Structural diversity of leucine-rich repeat proteins.
J Mol Biol. 1998; 277: 519-27
Display abstract
The superfamily of leucine-rich repeat proteins can be subdivided into at least six subfamilies, characterised by different lengths and consensus sequences of the repeats. It was proposed that the repeats from different subfamilies retain a similar superhelical fold, but differ in the three-dimensional structures of individual repeats. The sequence-structure relationship of three new subfamilies was examined by molecular modelling. I provide structural models for the repeats of all subfamilies. The models enable me to explain residue conservations within each subfamily. Furthermore, the difference in the packing explains why the repeats from different subfamilies never occur simultaneously in the same protein. Finally, these studies suggest different evolutionary origins for the different subfamilies. The approach used for the prediction of the leucine-rich repeat protein structures can be applied to other proteins containing internal repeats of about 20 to 30 residue in length.
Hundreds of ankyrin-like repeats in functionally diverse proteins: mobile modules that cross phyla horizontally?
Proteins. 1993; 17: 363-74
Display abstract
Based on pattern searches and systematic database screening, almost 650 different ankyrin-like (ANK) repeats from nearly all phyla have been identified; more than 150 of them are reported here for the first time. Their presence in functionally diverse proteins such as enzymes, toxins, and transcription factors strongly suggests domain shuffling, but their occurrence in prokaryotes and yeast excludes exon shuffling. The spreading mechanism remains unknown, but in at least three cases horizontal gene transfer appears to be involved. ANK repeats occur in at least four consecutive copies. The terminal repeats are more variable in sequence. One feature of the internal repeats is a predicted central hydrophobic alpha-helix, which is likely to interact with other repeats. The functions of the ankyrin-like repeats are compatible with a role in protein-protein interactions.
Metabolism (metabolic pathways involving proteins which contain this domain)
Click the image to view the interactive version of the map in iPath
This information is based on mapping of SMART genomic protein database to KEGG orthologous groups. Percentage points are related to the number of proteins with LRRcap domain which could be assigned to a KEGG orthologous group, and not all proteins containing LRRcap domain. Please note that proteins can be included in multiple pathways, ie. the numbers above will not always add up to 100%.
