Shroom is a recently-described regulator of cell shape changes in the developing nervous system. This protein is a member of a small family of related proteins that are defined by sequence similarity and in most cases by some link to the actin cytoskeleton. At present these proteins are named Shroom, APX, APXL, and KIAA1202. In light of the growing interest in this family of proteins, we propose here a new standard nomenclature.
In 1992, the primary structure of an
Table 1. New nomenclature for Shroom-related proteins
From global multiple alignments of genomic sequences, it is clear that these proteins are not simply encoded by homologous genes. There are in fact four different proteins in this family, showing similarity in their domains (Table 2), which include a PDZ and two
Table 2. Sequence identity matrix for the four different Shroom proteins which have been characterised experimentally.
Bioinformatics-based searches identified Shroom-related proteins in all chordates examined. In addition, insect genomes, including Drosophila melanogaster, Anopheles gambiae and Apis mellifera, encode a partially related protein containing an ASD2 domain (Table 1). Finally, BLAST searches of the deposited sequences from invertebrate genome projects identify what may be considered Shroom orthologues in both Ciona intestinalis (data not shown) and Strongylocentrotus purpuratus (Table 1). Based on the putative open reading frames and genomic organization, these predicted proteins contain, at least, the N-terminal PDZ domain and the C-terminally positioned ASD2 motif.
To clarify future studies, we propose a unifying nomenclature, emphasizing the relatedness of those proteins (Table 1). We feel that while the founding member is Apx, this name is undesirable as a root for naming this family because it requires that 'Xenopus' would appear in protein names from all species. Instead, we propose that the new nomenclature be based upon the name 'Shroom' as this is now the most thoroughly studied member of the family [4-6]. An Arabic number following 'Shroom' would distinguish between the different proteins. A lower-case letter would distinguish between different protein products encoded by the same locus generated by alternative mRNA processing. According to these rules, we suggest the re-naming presented in Table 1.
Several papers suggest that these related proteins play diverse and important roles in the development of the nervous system and other tissues [2-8]. Future studies will be required to show if sequence similarity among Shroom protein family members is mirrored by conservation of their cellular and molecular function.
J Cell Biol 1992, 119(6):1497-1506. Publisher Full Text
Hum Mol Genet 1995, 4(3):373-382. PubMed Abstract
Hagens O, Dubos A, Abidi F, Barbi G, Van Zutven L, Hoeltzenbein M, Tommerup N, Moraine C, Fryns JP, Chelly J, van Bokhoven H, Gecz J, Dollfus H, Ropers HH, Schwartz CE, de Cassia Stocco Dos Santos R, Kalscheuer V, Hanauer A: Disruptions of the novel KIAA1202 gene are associated with X-linked mental retardation.