Kjemtrup S, Borkhsenious O, Raikhel N V, Chrispeels M J
Department of Biology, University of California, San Diego, La Jolla 92093-0116, USA.
Plant Physiol. 1995 Oct;109(2):603-10. doi: 10.1104/pp.109.2.603.
Phytohemagglutinin (PHA), an abundant vacuolar seed protein of the common bean (Phaseolus vulgaris), is a tetramer of two homologous polypeptides, PHA-E and PHA-L. The roots of bean seedlings release into the culture medium a cross-reacting lectin that is most closely related to PHA-E. Reverse-transcriptase polymerase chain reaction with root mRNA as template was used to identify PHA transcripts in the roots of bean seedlings. Roots were found to contain mRNA for PHA-E but not for PHA-L. Indirect immunocytochemical detection with colloidal gold and antibodies to deglycosylated PHA showed that in the meristem of the primary root, PHA accumulates in vacuoles. However, in elongated root cells PHA was found only in the cell walls, indicating targeting to an alternate location. These results are discussed in relation to the various mechanisms that may account for the release of a normally vacuolar protein by roots.
植物血凝素（PHA）是菜豆（Phaseolus vulgaris）中一种丰富的液泡种子蛋白，是由两种同源多肽PHA-E和PHA-L组成的四聚体。菜豆幼苗的根向培养基中释放一种与PHA-E关系最为密切的交叉反应凝集素。以根mRNA为模板进行逆转录聚合酶链反应，以鉴定菜豆幼苗根中的PHA转录本。发现根中含有PHA-E的mRNA，但不含PHA-L的mRNA。用胶体金和去糖基化PHA抗体进行间接免疫细胞化学检测表明，在初生根的分生组织中，PHA积累在液泡中。然而，在伸长的根细胞中，PHA仅存在于细胞壁中，表明其靶向另一个位置。结合可能解释根释放正常液泡蛋白的各种机制对这些结果进行了讨论。
