Protein expression in platelets from six species that differ in their open canalicular system

Wangsun Choi, Zubair A. Karim, Sidney W. Whiteheart

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Platelets contain an invaginated, tubular membranous structure called the surface-connected open canalicular system (SCCS or OCS), which is contiguous with the plasma membrane and serves as a site for granule fusion and as a reservoir of membrane for platelet spreading. According to ultrastructural studies, platelets from some species lack OCS. In an attempt to correlate biochemical and functional attributes with the presence of an OCS, platelets from human, mouse and dog (OCS), and from cow, camel and horse (OCS-) were analysed for differential protein expression and aggregation in response to thrombin. Among the 18 different cytoskeletal and regulatory proteins examined, five (Rac1, RhoA, Ras, calmodulin and Src) were expressed at higher levels in OCS platelets (p < 0.05). Given the role of Arf6 in the formation of tubular invaginations in nucleated cells, the levels of Arf6-GTP were analysed in OCS and OCS- platelets. There was no significant correlation between the presence of OCS and total Arf6 or Arf6-GTP levels. Comparison of platelet aggregation between different species suggests that OCS- platelets have delayed responses. This comparison of platelets from six different species, which differ in their OCS, shows the differential expression of known signaling components and foreshadows future studies focusing on OCS formation and function.

Original languageEnglish
Pages (from-to)167-175
Number of pages9
Issue number3
StatePublished - 2010

Bibliographical note

Funding Information:
The authors are indebted to the members of the Whiteheart laboratory for their careful reading of and comments on this manuscript. The authors wish to thank Dr. Roy B. Burns DVM for his help and advice and the Louisville Zoological Gardens for access to their collection. We also wish to thank Dr. Karen J. McDowell, Department of Veterinary Sciences, Dr. Glen E. Aiken, Department of Plant and Soil Sciences, and the staff of the Department of Laboratory Animal Resources, University of Kentucky for their help in gathering samples. This work was supported by grants HL56652 and HL091893 from the National Institutes of Health (NIH) to SWW, and a predoctoral fellowship 0615112B from the AHA Great Rivers Affiliate to WC.


  • Aggregation
  • Cytoskeleton
  • Membrane structures
  • OCS
  • Small GTPase

ASJC Scopus subject areas

  • Hematology


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