Staphylokinase/Streptokinase (IPR004093)

Short name: SAK/SK

Overlapping homologous superfamilies

Family relationships

  • Staphylokinase/Streptokinase (IPR004093)


This entry represents staphylokinases and streptokinases.

Staphylokinase (also known as SAK) from Staphylococcus aureus is a virulence factor due to its interaction with plasminogen and alpha-defensins in the hosts. The binding of staphylokinase to plasminogen results in the formation of active plasmin, a proteolytic enzyme facilitating bacterial penetration into the surrounding tissues [PMID: 16111912]. However, once the host tissues are infected, the interaction between staphylokinase and plasminogen decreases disease severity [PMID: 23801604]. The three-dimensional structure of streptokinase [PMID: 9145104] is believed to contain two independently folded domains, each with a ubiquitin-like fold.

Streptokinase (SK) can be found in several species of Streptococci. It can bind not only plasminogen, but also host fibrinogen [PMID: 7565010]. This close interaction with the human fibrinolytic system allows the microbe to acquire unregulatable cell-surface enzymatic activity, promoting further spread from the site of infection. The complexes formed between streptococcal cells, streptokinase, plasminogen and fibrinogen can lyse fibrin clots in the host [PMID: 7565010]. Streptokinase has been used to treat acute myocardial infarction [PMID: 17948083].

GO terms

Biological Process

GO:0009405 pathogenesis
GO:0031639 plasminogen activation

Molecular Function

No terms assigned in this category.

Cellular Component

GO:0005576 extracellular region

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.