The Annexin Family

The annexins are a collection of proteins which have been isolated from a variety of tissues. They have been ascribed many biochemical properties and have been given names indicative of their presumed function and the tissues in which they were found. It is now appreciated that these apparently dissimilar proteins are part of the same group which share a conserved segment of some 80 aminoacids repeated up to 8 times in a single protein. The nomenclature of this group has been revised in order to simplify the field (Crumpton & Dedman, 1990) At the time of writing there where ten annexin groups, designated by roman numerals I-X. Some of these, including CAP-50 are known to be true annexins but have not yet been classified further. Only those which are known to bind actin are discussed below.  Annexins that contain KFERQ are degraded more quickly that those without the sequence (Cuervo et al, 2000).

References:-

Annexin I (Calpactin II, lipocortin I, p35, GIF, Chromobindin 9)  

Binds F-actin, but does not bundle, probably because the protein does not exist as a dimer. Annexin I has a motif similar to the putative annexin II actin binding domain (see below).  Binds F-actin, but does not bundle, probably because the protein does not exist as a dimer. Annexin I has a motif similar to the putative annexin II actin binding domain (see below). Annexin I is reported to bind profilin (Alvarez-Martinez et al, 1996), resulting in the prevention of actin-binding activity of profilin (Alvarez-Martinez et al, 1997), but as their are many other proteins that bind profilin other than actin (diaphanous, VASP etc) the significance of this interaction is not clear.

References:-

Alvarez-Martinez, M.-T., J.-C. Mani, et al. (1996). "Characterization of the interaction between annexin I and profilin." Eur.J.Biochem. 238, 777-784.

 Annexin II (Calpactin I, lipocortin II,p36, PAP-IV, Chromobindin 8, Protein I)   

Exists as a dimer apparently being held together by a "light chain" also called p11. Binds and bundles F-actin in a calcium dependent manner, this bundling activity is inhibited by the peptide VLIRIMVSR, corresponding to a putative actin binding domain in the protein.

References:-

Oliferenko, S., Paiha, K., Harder, T., Gerke, V., Schwarzler, C., Schwatrz, H., Beug, H., Gunthert, U. & Huber, L.A. (1999). "Analysis of CD44-containing lipid rafts: Recruitment of annexin II and stabilization by the actin cytoskeleton. J.Cell Biol. 146(4), 843-854.

Thiel, C., K. Weber, et al. (1991). "Characterization of a Ca²⁺-binding site in human annexin II by site-directed mutagenesis." J. Biol. Chem. 266, 14732-14739.

 Annexin III (lipocortin III, PAP III, 35-a-calcimedin)

References:-

Annexin IV (lipocortin IV, endonexin I, protein II, 32.5k-calelectrin, chromobindin 4, PAP II, PP4-X, 35-b-calcimedin)

References:-

AnnexinV (endonexin II, lipocortin V, 35K calelectrin, 35-g-calcimedin, PP4, IBC, PAP-I, VAC-a, calphobindin I, anchorin CII, thromboblastin inhibitor)

A 35kd 

References:-

Huber, R., J. Romisch, et al. (1990). "The crystal and molecular-structure of human annexin-v, an anticoagulant protein that binds to calcium and membranes." EMBO J  9,  3867-3874.

Annexin VI (lipocortin VI, Protein III, p70, p68, 73k, 67k, Calelectrin, Chromobindin 20, Calphobindin II)

A 68kd protein whose actin binding is positively reulagated by calcium (other actin binding proteins are typically negatively regulated by calcium). Annexin VI may bind G- as well as actin filaments and also binds lipids. Annexin VI has been localized to stress fibres, membrane ruffles, microspikes and focal contacts. On stress fibres annexin VI is periodic and coincident with a-actinin consistent with the fact that there is no competition between the two proteins. Annexin VI contains 8 annexin repeats.

References

Babiychuk, E. B.,  Palstra, R.-J. T. S., Schaller, J., Kampfer, U. & Draeger, A. (1999). "Annexin VI participates in the formation of a reversible, membrane-cytoskeleton complex in smooth muscle cells." J.Biol.Chem. 274(49), 35191-35195.

Grewal, T., Heeren, J., Mewawala, D., Schnitgerhans, T., Wendt, D., Salomon, G., Enrich, C., Beisiegel, U., & Jackle, S. (2000). "Annexin VI stimulates endocytosis and is involved in the trafficking of low density lipoprotein to the prelysosomal compartment." J.Biol.Chem. 275(43), 33806-33813.

Annexin VII (Synexin)                          

Originally isolated from adrenal medulla (Creutz et al, 1978, Burns et al, 1989), subsequently discovered in other tissues and in protists (Döring et al, 1991).

References

Burns, A.L., Magendzo, K., Shirvan, A., Srivastava, M., Rjas, E., Alijani, M.R., & Pollard, H.B. (1989). "" Proc.Nat.Acad.Sci. USA, 86, 3798-3802.

Creutz, C.E., Pazoles, C.J., & Pollard, H.B. (1978). "" J.Biol.Chem. 253, 2858-2866.

Annexin VIII (VAC-b)

References