Amino acid sequence analysis of the annexin super‐gene family of proteins

Abstract

The annexins are a widespread family of calcium-dependent membrane-binding proteins. No common function has been identified for the family and, until recently, no crystallographic data existed for an annexin. In this paper we draw together 22 available annexin sequences consisting of 88 similar repeat units, and apply the techniques of multiple sequence alignment, pattern matching, secondary structure prediction and conservation analysis to the characterisation of the molecules. The analysis clearly shows that the repeats cluster into four distinct families and that greatest variation occurs within the repeat 3 units. Multiple alignment of the 88 repeats shows amino acids with conserved physicochemical properties at 22 positions, with only Gly at position 23 being absolutely conserved in all repeats. Secondary structure prediction techniques identify five conserved helices in each repeat unit and patterns of conserved hydrophobic amino acids are consistent with one face of a helix packing against the protein core in predicted helices a, c, d, e. Helix b is generally hydrophobic in all repeats, but contains a striking pattern of repeat-specific residue conservation at position 31, with Arg in repeats 4 and Glu in repeats 2, but unconserved amino acids in repeats 1 and 3. This suggests repeats 2 and 4 may interact via a buried saltbridge. The loop between predicted helices a and b of repeat 3 shows features distinct from the equivalent loop in repeats I, 2 and 4, suggesting an important structural and/or functional role for this region. No compelling evidence emerges from this study for uteroglobin and the annexins sharing similar tertiary structures, or for uteroglobin representing a derivative of a primordial one-repeat structure that underwent duplication to give the present day annexins. The analyses performed in this paper are re-evaluated in the Appendix, in the light of the recently published X-ray structure for human annexin V. The structure confirms most of the predictions and shows the power of techniques for the determination of tertiary structural information from the amino acid sequences of an aligned protein family.The annexins are a family of proteins that share the common features of binding both membranes and phospholipids in a Ca2 +-dependent manner. The annexins are found in many tissues, and their membrane binding activity has been claimed to be involved in cytoskeletal interactions [I] Abbreviations. AI-AX, annexins I-X; AI, annexin I; AII, annexin 11; AIII, annexin 111; AVI, annexin VI; AVII, annexin VII; AIX, annexin IX; AX, annexin X; AIH etc., human annexin I etc.; AIP etc., porcine annexin I etc.; AIR etc., rat annexin I etc.; AIIH etc., human annexin I1 etc.; AIIM etc., murine annexin I1 etc.; AIIB etc., bovine annexin 11 etc.; AIXD etc., Drosophila annexin IX etc.;AIH2 etc., human annexin I repeat 2; AIIxl, human, murine and bovine annexin I1 repeat 1 ; AIVx2, human, porcine and bovine annexin IV repeat 2; AIVx4, AIVH4, AIVP4 and AIVB4 together; AVIx58, human and murine annexin VI, from...

Proteome differences associated with fat accumulation in bovine subcutaneous adipose tissues

“…The annexins (or lipocortins) are a family of proteins that are ubiquitously distributed in different tissues and cell types of higher and lower eukaryotes, including mammals, fish, and birds [28]. This protein functions as calcium-dependent phospholipid-binding protein [29].…”

Mapping of three unique Ca2+‐binding sites in human annexin II

“…A mutation in the latter positions probably causes a distortion of the loop formed by this portion of the endonexin fold whose correct dimensions are important for Ca2+ complexation. Evidence for the existence of a loop in the region surrounding Gly206 in annexin I1 stems from secondary structure predictions (Barton et al, 1991) and proteolysis studies. The peptide bond between Arg204 and Lys205, i.e.…”

Dynamic reciprocity: the role of annexin A2 in tissue integrity

“…Annexin A2 is a 36 kDa protein made up of an N-terminal domain and the annexin familyconserved endonexin fold in the C-terminal domain (Barton et al, 1991). The endonexin fold consists of four 70-amino acid repeats which form alpha-helices and binds Ca 2+ ions (Barton et al, 1991).…”