Thrombin generates syndecan ectodomain fragments.

To aid our understanding of the decrease in S3ED/S4ED proteins, western blots were carried out with recombinant syndecan ectodomains treated with thrombin. (A) Neither rhS1ED or rhS2ED were found to be cleaved by thrombin (10 U/ml, 24 hours). (B) In contrast, rhS3ED and rhS4ED were both cleaved by thrombin (10 U/ml, 24 hours) to produce 4 and 1 fragments respectively (labelled a-e). (C) A shorter treatment time with thrombin of 1 hour was sufficient to cleave and generate the same rhS3ED (a-d) and rhS4ED (e) fragments. (D) Probing of the SDC fragments with anti-6-his tag showed three of the four rhS3ED fragments all contain the C-terminal 6-his tag, whilst the rhS4ED fragment generate through thrombin treatment did not contain the 6-his tag. (E) A schematic to illustrate the probable identities of some of the different SDC ectodomain fragments generated by thrombin based on evidence from western blots. Western blots shown are representative images of n = 3. Arrowhead indicates position of thrombin on blot.