Shimizu Munetaka, Fujiwara Yumi, Fukada Haruhisa, Hara Akihiko
School of Aquatic and Fishery Sciences, Box 355020, University of Washington, Seattle, Washington 98195, USA.
J Exp Zool. 2002 Dec 1;293(7):726-35. doi: 10.1002/jez.10178.
Estrogen treatment of medaka leads to accumulation of ascites, in which vitellogenin (Vg) and choriogenins (precursors to vitelline envelope) are abundant. Besides those female-specific proteins, we detected a new component in ascites that cross-reacts with antiserum against egg yolk proteins. We tentatively named it egg yolk-related protein (YRP). YRP was purified from ascites by hydroxylapatite chromatography followed by gel filtration. Purified YRP had a molecular mass of 460 kDa in intact state while 570 kDa for Vg. The molecular weight of purified YRP on SDS-PAGE under both reducing and nonreducing conditions was 130 kDa. YRP was confirmed to be a lipoglycophosphoprotein by staining with Sudan black, periodic acid-Schiff (PAS) and methyl green. Amino acid composition of YRP resembled that of Vg except for a relatively low content of serine. A specific antiserum against YRP was raised in a rabbit. Antiserum against YRP specifically immunostained its antigen but not Vg or choriogenins. YRP was detected as a female-specific protein in serum of breeding medaka. The antiserum also cross-reacted with a band at 29 kDa in egg extracts, which is not immunoreactive to antiserum against Vg. These data show that YRP is a precursor to some egg yolk proteins with differing antigenicity from Vg (Hamazaki et al. '87). We thus conclude that YRP is a second form of medaka Vg and rename YRP as Vg 2 while formerly reported Vg as Vg 1.
用雌激素处理青鳉会导致腹水积聚，腹水中富含卵黄蛋白原（Vg）和卵壳蛋白原（卵黄膜前体）。除了这些雌性特异性蛋白外，我们在腹水中检测到一种新成分，它能与抗卵黄蛋白抗血清发生交叉反应。我们暂时将其命名为卵黄相关蛋白（YRP）。通过羟基磷灰石色谱法随后进行凝胶过滤从腹水中纯化YRP。完整状态下纯化的YRP分子量为460 kDa，而Vg为570 kDa。在还原和非还原条件下，SDS-PAGE上纯化的YRP分子量均为130 kDa。通过苏丹黑、过碘酸-希夫（PAS）和甲基绿染色证实YRP是一种脂糖磷蛋白。YRP的氨基酸组成与Vg相似，只是丝氨酸含量相对较低。用兔子制备了针对YRP的特异性抗血清。抗YRP抗血清特异性免疫染色其抗原，但不与Vg或卵壳蛋白原反应。在繁殖期青鳉的血清中检测到YRP是一种雌性特异性蛋白。该抗血清还与卵提取物中一条29 kDa的条带发生交叉反应，该条带对抗Vg抗血清无免疫反应。这些数据表明YRP是一些卵黄蛋白的前体，其抗原性与Vg不同（滨崎等人，1987年）。因此，我们得出结论，YRP是青鳉Vg的第二种形式，并将YRP重新命名为Vg 2，而之前报道的Vg命名为Vg 1。
