Structural determinant of the vesicle aggregation activity of annexin I.
Some annexins, including annexins I, II, IV, and VII, can promote membrane aggregation. To identify amino acids involved in annexin I-mediated membrane aggregation, we generated truncated mutants of human annexin I lacking various parts of the amino terminus. The in vitro vesicle binding and aggregation activities of these mutants indicated that both the amino-terminal region of annexin I spanning residues 26-29 and the carboxy-terminal core are involved in membrane aggregation. This notion was further supported by the finding that a chimera composed of residues 24-35 of annexin I and the core of annexin V has vesicle aggregation activity that is significantly higher than that of annexin V but lower than that of annexin I. Further site-specific mutations in the amino-terminal region of annexin I indicated that Lys-26 and Lys-29 are essential for its membrane aggregation activity. The comparison of tryptic digest patterns of free and vesicle-bound wild type and K29E mutant suggests that a primary role of Lys-26 and Lys-29 is to induce and stabilize an active conformation of annexin I for vesicle aggregation.
Bitto
E
E
Department of Chemistry, University of Illinois at Chicago 60607-7061, USA.
Cho
W
W
D000595:Amino Acid Sequence; D017305:Annexin A1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D017384:Sequence Deletion; D012694:Serine / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship
D017305:Annexin A1; D008565:Membrane Proteins; D010446:Peptide Fragments; D010743:Phospholipids; D011993:Recombinant Fusion Proteins; D012694:Serine; D008239:Lysine