Tatsuya Kato1, Dongning Du2, Fumiaki Suzuki3, and Enoch Y. Park2. (1) Department of Applied Biological Chemistry, Shizuoka University, 836 Ohya Suruga-ku, Shizuoka, 422-8529, Japan, (2) Laboratory of Biotechnology, Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan, (3) Laboratory of Animal Biochemistry, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
Human (pro)renin receptors (hPRR) with native putative transmembrane and cytoplasmic domains (hPRR-wTM) were purified from the microsomal fraction of baculovirus-infected Tn-5B1-4 cells. However, hPRR produced with deleted transmembrane and cytoplasmic domains (hPRR-w/oTM) could not be adequately purified. In this report, the expression of hPRR-wTM and hPRR-w/oTM was analysed. hPRR-w/oTM was detected in budded baculovirus (BV) fractions isolated from culture supernatant, whilst hPRR-wTM was not. This suggests that hPRR-w/oTM might be associated with BV. hPRR was expressed in the peripheral domains of the nucleus in infected Sf-9 cells. In contrast, hPRR-w/oTM was observed in punctate domains in the cytoplasm, indicating that hPRR-wTM and hPRR-w/oTM localized in the endoplasmic reticulum (ER) and cytoplasmic organelles, respectively. Moreover, intracellular hPRR-w/oTM did not co-localize in the Golgi apparatus and lysosomes. hPRR-wTM could not be extracted from infected Sf-9 and Tn-5B1-4 cells by Triton X-100 treatment at 4°C. It is suggested that hPRR-wTM might not reside in the plasma membrane and that localization of hPRR-wTM in the ER might result in a lack of association with the BV. hPRR-w/oTM was detected in the BV fraction despite lacking a transmembrane domain, but was not detected in the virus envelope fraction, suggesting that hPRR-w/oTM might be associated with other areas in the BV.