Jensen P E, Arbelaez L F, Shanbhag V P, Stigbrand T
Department of Immunology, University of Umeå, Sweden.
Biochim Biophys Acta. 1996 Apr 16;1293(2):254-8. doi: 10.1016/0167-4838(95)00257-x.
Digestion of the pregnancy zone protein with papain at pH 4.5 yields an 18 kDa C-terminal fragment. This fragment consists of the 145 C-terminal amino-acid residues cleaved at Asn-1288 Ile and is homologous to the C-terminal receptor binding fragment of human alpha 2-macroglobulin obtained by cleavage with papain. The fragment contains an intrachain disulfide bond between 1308Cys and 1423Cys corresponding to that between 1304Cys and 1419Cys in alpha 2-macroglobulin. An oligosaccharide chain, is present in the C-terminal fragment of pregnancy zone protein as in human alpha 2-macroglobulin. The PZP C-terminal fragment was demonstrated to bind to the LRP/alpha 2M-receptor. Both the pregnancy zone protein and alpha 2-macroglobulin fragments bind three mAb's (alpha 1:1, R35, and 7H11D6) generated against alpha 2-macroglobulin. The mAb 7H11D6 was generated against the alpha 2-macroglobulin-proteinase complex (Isaacs, I.J., Steiner, J.P., Roche, P.A., Pizzo, S.V. and Strickland, D.K. (1988) J. Biol. Chem. 263, 6709-6714) and the binding of this to the C-terminal fragments of both pregnancy zone protein and alpha 2-macroglobulin indicates that both proteins use the same receptor recognition site for binding to the LRP/alpha 2M-receptor.
在pH 4.5条件下用木瓜蛋白酶消化妊娠区蛋白可产生一个18 kDa的C端片段。该片段由在Asn-1288 Ile处切割的145个C端氨基酸残基组成，与用木瓜蛋白酶切割得到的人α2-巨球蛋白的C端受体结合片段同源。该片段在1308Cys和1423Cys之间含有一个链内二硫键，与α2-巨球蛋白中1304Cys和1419Cys之间的二硫键相对应。与人类α2-巨球蛋白一样，妊娠区蛋白的C端片段中存在一条寡糖链。已证明妊娠区蛋白C端片段可与LRP/α2M受体结合。妊娠区蛋白和α2-巨球蛋白片段均能结合三种针对α2-巨球蛋白产生的单克隆抗体（α1:1、R35和7H11D6）。单克隆抗体7H11D6是针对α2-巨球蛋白-蛋白酶复合物产生的（艾萨克斯，I.J.，施泰纳，J.P.，罗氏，P.A.，皮佐，S.V.和斯特里克兰，D.K.（1988年）《生物化学杂志》263卷，6709 - 6714页），其与妊娠区蛋白和α2-巨球蛋白的C端片段的结合表明这两种蛋白利用相同的受体识别位点与LRP/α2M受体结合。
