Pikaard C S, Brusca J S, Hannapel D J, Park W D
Nucleic Acids Res. 1987 Mar 11;15(5):1979-94. doi: 10.1093/nar/15.5.1979.
The major potato tuber protein, patatin, is a family of 40kd glycoproteins that constitutes forty per cent of the soluble protein in tubers but is generally undetectable in other tissues. Fused rocket immunoelectro-phoresis was used to detect in roots patatin that is immunologically different from tuber patatin. Western blots of SDS-polyacrylamide gels show root patatin to have a different molecular weight distribution than tuber patatin isoforms, but immunoprecipitation of in vitro translation products shows the patatin precursors to be of similar molecular weight in both tissues. This suggests that post-translational processing may differ in tubers and roots. Northern blots show that tuber and root patatin mRNAs are of similar size, but tuber transcripts are about 100-fold more abundant. 5' S1 nuclease and primer extension mapping suggests the class of patatin transcripts expressed in roots (class II transcripts) to be a subset of patatin transcripts expressed in tubers (classes I and II). Class II patatin mRNAs differ from class I transcripts by the presence of a 22 nucleotide insertion just upstream of the initiation codon. These data demonstrate that expression of the patatin multigene family is differentially regulated in tubers and roots.
马铃薯块茎的主要蛋白质——马铃薯素，是一类40kd的糖蛋白，占块茎可溶性蛋白的40%，但在其他组织中通常检测不到。采用融合火箭免疫电泳法在根中检测到与块茎马铃薯素免疫不同的马铃薯素。SDS-聚丙烯酰胺凝胶的Western印迹显示，根中的马铃薯素与块茎马铃薯素同工型具有不同的分子量分布，但体外翻译产物的免疫沉淀显示，两种组织中马铃薯素前体的分子量相似。这表明翻译后加工在块茎和根中可能有所不同。Northern印迹显示，块茎和根中的马铃薯素mRNA大小相似，但块茎转录本的丰度约高100倍。5'S1核酸酶和引物延伸图谱表明，根中表达的马铃薯素转录本（II类转录本）是块茎中表达的马铃薯素转录本（I类和II类）的一个子集。II类马铃薯素mRNA与I类转录本的不同之处在于，起始密码子上游刚好存在一个22个核苷酸的插入序列。这些数据表明，马铃薯素多基因家族的表达在块茎和根中受到差异调节。
