Family

Annexin, type XI (IPR008157)

Short name: AnnexinXI

Family relationships

  • Annexin (IPR001464)
    • Annexin, type XI (IPR008157)

Description

The annexins (or lipocortins) are a family of proteins that bind to phospholipids in a calcium-dependent manner [PMID: 1646719]. They are distributed ubiquitously in different tissues and cell types of higher and lower eukaryotes, including mammals, fish, birds, Drosophila melanogaster (Fruit fly), Xenopus laevis (African clawed frog), Caenorhabditis elegans , Dictyostelium discoideum (Slime mold) and Neurospora crassa [PMID: 9797403, PMID: 9165068]. Annexins are absent from yeasts and prokaryotes [PMID: 15059252]. The plant annexins are somewhat distinct from those found in other taxa [PMID: 9165068].

Most eukaryotic species have 1-20 annexin (ANX) genes. All annexins share a core domain made up of four similar repeats, each approximately 70 amino acids long [PMID: 1646719]. Each individual annexin repeat (sometimes referred to as endonexin folds) is folded into five alpha-helices, and in turn are wound into a right-handed super-helix; they usually contain a characteristic 'type 2' motif for binding calcium ions with the sequence 'GxGT-[38 residues]-D/E'. Animal and fungal annexins also have variable amino-terminal domains. The core domains of most vertebrate annexins have been analysed by X-ray crystallography, revealing conservation of their secondary and tertiary structures despite only 45-55% amino-acid identity among individual members. The four repeats pack into a structure that resembles a flattened disc, with a slightly convex surface on which the Ca 2+ -binding loops are located and a concave surface at which the amino and carboxyl termini come into close apposition.

Annexins are traditionally thought of as calcium-dependent phospholipid-binding proteins, but recent work suggests a more complex set of functions. The famiy has been linked with inhibition of phospholipase activity, exocytosis and endoctyosis, signal transduction, organisation of the extracellular matrix, resistance to reactive oxygen species and DNA replication [PMID: 9797403].

This entry represents Annexin type XI. The N-terminal of annexin XI is hydrophobic, rich in glycine, tyrosine, and proline residues, and is larger than that of the other annexin members. Annexin XI is ubiquitously expressed in a variety of tissues and cell types of eukaryotes, but its subcellular distribution varies considerably. Some growth and differentiation conditions favour the presence of annexin XI in the nucleus, whereas others favour either a cytoplasmic distribution or both. Annexin XI is upregulated in mitotic cells and stains mitotic spindles. Ca2+ was found to influence both the association of annexin XI with tubulin and the nuclear or cytoplasmic subcellular localisation of annexin XI [PMID: 12805373].

The human orthologue of annexin XI was found to be identical to the 56K autoantigen, found in individuals with a range of autoimmune diseases such as rheumatoid arthritis [PMID: 7508441].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0005509 calcium ion binding
GO:0005544 calcium-dependent phospholipid binding

Cellular Component

No terms assigned in this category.

Contributing signatures

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