Corpas F J, Sandalio L M, Brown M J, del Río L A, Trelease R N
Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín, CSIC, Apdo. 419, E-18080 Granada, Spain.
Plant Cell Physiol. 2000 Nov;41(11):1218-28. doi: 10.1093/pcp/pcd054.
A 36-kDa polypeptide of unknown function was identified by us in the boundary membrane fraction of cucumber seedling glyoxysomes. Evidence is presented in this study that this 36-kDa polypeptide is a glyoxysomal membrane porin. A sequence of 24 amino acid residues derived from a CNBr-cleaved fragment of the 36-kDa polypeptide revealed 72% to 95% identities with sequences in mitochondrial or non-green plastid porins of several different plant species. Immunological evidence indicated that the 36-kDa (and possibly a 34-kDa polypeptide) was a porin(s). Antiserum raised against a potato tuber mitochondrial porin recognized on immunoblots 34-kDa and 36-kDa polypeptides in detergent-solubilized membrane fractions of cucumber seedling glyoxysomes and mitochondria, and in similar glyoxysomal fractions of cotton, castor bean, and sunflower seedlings. The 36-kDa polypeptide seems to be a constitutive component because it was detected also in membrane protein fractions derived from cucumber leaf-type peroxisomes. Compelling evidence that one or both of these polypeptides were authentic glyoxysomal membrane porins was obtained from electron microscopic immunogold analyses. Antiporin IgGs recognized antigen(s) in outer membranes of glyoxysomes and mitochondria. Taken together, the data indicate that membranes of cucumber (and other oilseed) glyoxysomes, leaf-type peroxisomes, and mitochondria possess similar molecular mass porin polypeptide(s) (34 and 36 kDa) with overlapping immunological and amino acid sequence similarities.
我们在黄瓜幼苗乙醛酸循环体的界膜组分中鉴定出一种功能未知的36 kDa多肽。本研究提供的证据表明，这种36 kDa多肽是乙醛酸循环体膜孔蛋白。从36 kDa多肽的CNBr裂解片段获得的一段24个氨基酸残基的序列，与几种不同植物物种的线粒体或非绿色质体孔蛋白序列具有72%至95%的同一性。免疫学证据表明，36 kDa（可能还有一种34 kDa多肽）是一种孔蛋白。针对马铃薯块茎线粒体孔蛋白产生的抗血清，在免疫印迹中识别出黄瓜幼苗乙醛酸循环体和线粒体去污剂溶解膜组分以及棉花、蓖麻和向日葵幼苗类似乙醛酸循环体组分中的34 kDa和36 kDa多肽。36 kDa多肽似乎是一种组成成分，因为在来自黄瓜叶型过氧化物酶体的膜蛋白组分中也检测到了它。通过电子显微镜免疫金分析获得了令人信服的证据，证明这些多肽中的一种或两种是真正的乙醛酸循环体膜孔蛋白。抗孔蛋白IgG识别乙醛酸循环体和线粒体外膜中的抗原。综上所述，数据表明黄瓜（和其他油料种子）乙醛酸循环体、叶型过氧化物酶体和线粒体的膜具有相似分子量的孔蛋白多肽（34 kDa和36 kDa），具有重叠的免疫学和氨基酸序列相似性。
