Structure of thrombospondin

The NH2-terminal amino acid sequences of thrombospondin and of a 30,000-Da heparin-binding peptide derived from thrombospondin by treatment with plasmin are identical. The heparin-binding peptide is homogeneous in size but slightly heterogeneous in charge with the predominant isoelectric points bein...

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Bibliographic Details
Published in:The Journal of biological chemistry 1984-03, Vol.259 (6), p.3944-3948
Main Authors: Coligan, J E, Slayter, H S
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Biological and medical sciences
Blood coagulation. Blood cells
Blood Platelets - analysis
Electrophoresis, Polyacrylamide Gel
Fibrinolysin
Fundamental and applied biological sciences. Psychology
Glycoproteins
Humans
Microscopy, Electron
Molecular and cellular biology
Peptide Fragments - analysis
Platelet
Thrombospondins
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Summary:The NH2-terminal amino acid sequences of thrombospondin and of a 30,000-Da heparin-binding peptide derived from thrombospondin by treatment with plasmin are identical. The heparin-binding peptide is homogeneous in size but slightly heterogeneous in charge with the predominant isoelectric points being 6.1 and 5.7. Electron microscopy of tungsten replicas of thrombospondin reveals a tripartite structure resembling a “bola” which is about 60 nm across when fully extended. Each part of the molecule terminates in a globular node or head which disappears upon limited plasmin digestion, suggesting that the heparin-binding peptide is located in the head region. In addition to the heparin-binding peptide, a 20,000-Da peptide also apparently associated with the head region is liberated during proteolysis. The electron micrographs indicate that the legs of the bola-like structure must be folded into an extended, flexible, tertiary structure. These legs, each of about 65,000 Da, appear to be attached near the ends opposite the heads, probably by disulfide bonds. Each leg possesses a tab or protein (approximately 20,000 Da) which juts out from this attachment point.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(17)43187-5