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Thromb Haemost 1996; 75(04): 623-629
DOI: 10.1055/s-0038-1650333
Original Article
Schattauer GmbH Stuttgart

The Lysosomal Granule Membrane Protein, Lamp-2, Is also Present in Platelet Dense Granule Membranes

S J Israels
The Departments of Pediatrics and Oral Biology and the Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba, Canada
,
E M McMillan
The Departments of Pediatrics and Oral Biology and the Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba, Canada
,
C Robertson
The Departments of Pediatrics and Oral Biology and the Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba, Canada
,
S Singhroy
The Departments of Pediatrics and Oral Biology and the Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba, Canada
,
A McNicol
The Departments of Pediatrics and Oral Biology and the Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba, Canada
› Author Affiliations
Further Information

Publication History

Received 31 May 1995

Accepted after revision 12 January 1996

Publication Date:
10 July 2018 (online)

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Summary

Lysosomal Associated Membrane Protein-2 (LAMP-2) is an inherent component of lysosomal granule membranes in diverse cell types, including platelets. We examined platelets for evidence of LAMP-2 in dense granule membranes as CD63 has previously been shown to be present in both lysosomal and dense granule membranes. Immunological techniques were used to examine the localization of LAMP-2 in control platelets and those from an individual with Hermansky-Pudlak syndrome (HPS), a condition characterised by platelet dense granule deficiency. Immunoblotting studies demonstrated that LAMP-2 was enriched in a dense granule preparation. Flow cytometry of thrombin-stimulated control platelets was consistent with biphasic surface expression of LAMP-2. The early expression was accompanied by dense granule, but minimal lysosomal granule, release. The late expression was accompanied by additional lysosomal granule release only. Thrombin stimulation of HPS platelets showed only late, lysosome-associated LAMP-2 expression. Immunoelectron microscopy indicated the presence of LAMP-2 in the membranes of serotonin-containing granules as identified by an anti-serotonin polyclonal antibody. These data indicate that LAMP-2 is present in the membranes of platelet dense granules in addition to lysosomal granules, and has a similar distribution to CD63.