| complement 4 | The second component to react in the complement sequence. It is a beta-globulin with a sedimentation coefficient of 18.7, a molecular weight of 240,000 and a serum concentration of 430 micrograms/ml. It is activated by complement 1 and serves as a receptor for c2. (12 Dec 1998) |
|---|---|
| complement 4a | <chemical> Smaller fragment formed when c1s splits c4 into c4a and c4b. As an anaphylatoxin, c4a causes symptoms of immediate hypersensitivity but it has weaker activity than c3a or c5a. Chemical name: Complement C4a (12 Dec 1998) |
| complement 4b | <chemical> Larger fragment formed when c1s splits c4 into c4a and c4b. C4b combines with c2b to form the activated c4b2b complex which is often called the classical pathway c3 convertase. Chemical name: Complement C4b (12 Dec 1998) |
| complement 5 | The fifth component in the complement reaction sequence, probably exists in a complex with c6 and c7. It is a beta-globulin with a sedimentation coefficient of 10, serum concentration of 75 micrograms/ml and molecular weight of 180,000. It is activated by c423 and releases fragments with anaphylatoxic, chemotactic, and histamine-releasing actions and affecting smooth muscle. (12 Dec 1998) |
| complement 5a | <chemical> Smaller fragment formed when c5 convertase splits c5 into c5a and c5b. C5a is a 74-amino acid peptide that includes a carboxy-terminal arginine crucial for its spasmogenic activity and a carbohydrate moiety. C5a is the most potent anaphylatoxin mediating immediate hypersensitivity. Chemical name: Complement C5a (12 Dec 1998) |
| complement 5a, des-arginine | Complement 5a with the carboxy-terminal arginine removed. The arginine is rapidly cleaved from the c5a fragment during complement activation by carboxypeptidase b present in normal human serum. C5a des-arg shows complete loss of spasmogenic activity though it retains some chemotactic ability. (12 Dec 1998) |
| complement 6 | The sixth component in the complement reaction sequence. It is a beta-globulin with a sedimentation coefficient of 8.7 and a molecular weight of 120,000 at 60 micrograms/ml in serum. It may exist in a complex with c5 and c7 and is activated by the binding of c5. (12 Dec 1998) |
| complement 7 | The seventh component in the complement reaction sequence. It is a beta-globulin probably in a complex with c5 and c6 and is activated by c5. The attachment of c7 renders the cell susceptible to lysis. (12 Dec 1998) |
| complement 8 | The next to the last essential component for cell lysis in the complement reaction sequence. It is a gamma-globulin with a molecular weight of 150,000 and a sedimentation coefficient of 8. It is present in trace amounts in serum and can be inhibited, like complement 1, by cation chelators. (12 Dec 1998) |
| complement 9 | The last component in the complement reaction sequence. It is an alpha-globulin present in serum as a trace, with a molecular weight of 80,000 and a sedimentation coefficient of 4.5. For cell lysis, it can be replaced by a metal chelator. (12 Dec 1998) |
| complement activating enzymes | <enzyme> Enzymes present in the complement system which activate one or more components in the system. Registry number: EC 3.- (12 Dec 1998) |
| complement activation | The sequential activation of serum components c1 through c9, initiated by an erythrocyte-antibody complex or by microbial polysaccharides and properdin, and producing an inflammatory response. (12 Dec 1998) |
| complement binding assay | A test for the detection of immune complexes. (05 Mar 2000) |
| complement chemotactic factor | The activated complex of the fifth, sixth, and seventh components of complement (C567) which induces chemotaxis in the case of polymorphonuclear leukocytes. (05 Mar 2000) |
| complement cytolysis inhibitor | <protein> Vertebrate glycoprotein of uncertain function. Secreted as a 400 amino acid peptide, then cleaved to form two 200 amino acid peptides that are linked by a disulphide bridge. Synonym: complement associated protein, complement cytolysis inhibitor, glycoprotein III. (11 Jan 1998) |