PMID: 6203908

 

    Legend: Sugar

Title : Primary structure of human alpha 2-macroglobulin

Abstract :
  1. V
  2. The complete structure
  3. The primary structure of the tetrameric plasma glycoprotein human alpha 2-macroglobulin has been determined
  4. The identical subunits contain 1451 amino acid residues
  5. Glucosamine-based oligosaccharide groups are attached to asparagine residues 32, 47, 224, 373, 387, 846, 968, and 1401
  6. Eleven intra chain disulfide bridges have been placed (Cys25-Cys63, Cys228-Cys276, Cys246-Cys264, Cys255-Cys408, Cys572-Cys748, Cys619-Cys666, Cys798-Cys826, Cys824-Cys860, Cys898-Cys1298, Cys1056-Cys1104, and Cys1329-Cys1444)
  7. Cys-447 probably forms an inter chain bridge with Cys-447 from another subunit
  8. The beta-SH group of Cys-949 is thiol esterified to the gamma-carbonyl group of Glx-952, thus forming an activatable reactive site which can mediate covalent binding of nucleophiles
  9. A putative transglutaminase cross-linking site is constituted by Gln-670 and Gln-671
  10. The primary sites of proteolytic cleavage in the activation cleavage area (the "bait" region ) are located in the sequence: -Arg681-Val-Gly-Phe-Tyr-Glu-
  11. The molecular weight of the unmodified alpha 2-macroglobulin subunit is 160,837 and approximately 179,000, including the carbohydrate groups
  12. The presence of possible internal homologies within the alpha 2-macroglobulin subunit is discussed
  13. A comparison of stretches of sequences from alpha 2-macroglobulin with partial sequence data for complement components C3 and C4 indicates that these proteins are evolutionary related
  14. The properties of alpha 2-macroglobulin are discussed within the context of proteolytically regulated systems with particular reference to the complement components C3 and C4