Hemese, a hemocyte-specific transmembrane protein, affects the cellular immune response in Drosophila

Kurucz, Éva and Zettervall, Carl-Johan and Sinka, Rita and Vilmos, Péter and Pivarcsi, Andor and Ekengren, Sophia and Hegedüs, Zoltán and Andó, István and Hultmark, Dan (2003) Hemese, a hemocyte-specific transmembrane protein, affects the cellular immune response in Drosophila. Proceedings of the National Academy of Sciences of the United States of America, 100 (5). pp. 2622-2627. ISSN 1091-6490

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Abstract

We have identified a previously undescribed transmembrane protein, Hemese, from Drosophila melanogaster blood cells (hemocytes), by using a monoclonal pan-hemocyte antibody. Heavy glycosylation is suggested by the heterogeneous size distribution, ranging between 37 and 70 kDa. Hemese expression is restricted to the cell surfaces of hemocytes of all classes, and to the hematopoietic organs. The sequence of the corresponding gene, Hemese (He), predicts a glycophorin-like protein of 15 kDa, excluding an N-terminal signal peptide, with a single hydrophobic transmembrane region. The extracellular region consists mainly of Ser/Thr-rich sequence of low complexity, with several potential O-glycosylation sites. Hemese contains phosphotyrosine and the cytoplasmic region has potential phosphorylation sites, suggesting an involvement in signal transduction. Depletion of Hemese by RNA interference has no obvious effect under normal conditions, but the cellular response to parasitic wasps is much enhanced. This finding indicates that Hemese plays a modulatory role in the activation or recruitment of the hemocytes.

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