tailieunhanh - Báo cáo khoa học: Zinc-binding property of the major yolk protein in the sea urchin ) implications of its role as a zinc transporter for gametogenesis

Major yolk protein (MYP), a transferrin superfamily protein that forms yolk granules in sea urchin eggs, is also contained in the coelomic fluid and nutritive phagocytes of the gonad in both sexes. MYP in the coelo-mic fluid (CFMYP; 180 kDa) has a higher molecular mass than MYP in eggs (EGMYP; 170 kDa). | ỊFEBS Journal Zinc-binding property of the major yolk protein in the sea urchin - implications of its role as a zinc transporter for gametogenesis Tatsuya Unuma1 Kazuo Ikeda2 Keisuke Yamano3 Akihiko Moriyama4 and Hiromi Ohta5 1 Japan Sea NationalFisheries Research Institute Fisheries Research Agency Suido-cho Niigata Japan 2 Kamiura Station NationalResearch Institute of Aquaculture Fisheries Research Agency Kamiura Oita Japan 3 NationalResearch Institute of Aquaculture Fisheries Research Agency Minami-ise Mie Japan 4 Graduate Schoolof NaturalSciences Nagoya City University Japan 5 Department of Fisheries Schoolof Agriculture Kinki University Nara Japan Keywords major yolk protein oogenesis sea urchin spermatogenesis zinc Correspondence T. Unuma Japan Sea NationalFisheries Research Institute Fisheries Research Agency Suido-cho Niigata 951-8121 Japan Fax 81 25 2240950 Tel 81 25 2280451 E-mail unuma@ Received 25 April2007 revised 11 June 2007 accepted 27 July 2007 doi Major yolk protein MYP a transferrin superfamily protein that forms yolk granules in sea urchin eggs is also contained in the coelomic fluid and nutritive phagocytes of the gonad in both sexes. MYP in the coelomic fluid CFMYP 180 kDa has a higher molecular mass than MYP in eggs EGMYP 170 kDa . Here we show that MYP has a zinc-binding capacity that is diminished concomitantly with its incorporation from the coelomic fluid into the gonad in the sea urchin Pseudocentrotus depressus. Most of the zinc in the coelomic fluid was bound to CFMYP whereas zinc in eggs was scarcely bound to EGMYP. Both CFMYP and EG-MYP were present in nutritive phagocytes where CFMYP bound more zinc than EGMYP. Saturation binding assays revealed that CFMYP has more zinc-binding sites than EGMYP. Labeled CFMYP injected into the coelom was incorporated into ovarian and testicular nutritive phagocytes and vitellogenic oocytes and the molecular mass of part of the incorporated CFMYP .