Patty L R, Lee J M, Ellstrand N C
Department of Biochemistry, University of California, Riverside 92521.
Biochem Genet. 1988 Feb;26(1-2):123-30. doi: 10.1007/BF00555493.
Detailed interpretation of triose phosphate isomerase (TPI) isozymes in seed plants has been restricted to only a few species. Three sets of TPI bands are regularly observed in the cherimoya (Annona cherimola), a primitive angiosperm. The slowest, set I, is expressed as one or three bands; the second-slowest set II, as one or two bands; and the fastest, set IV, as one or three bands. A faint set III, just cathodal to set IV, is detected rarely with overstaining. Set IV bands are expressed in macerated extracted pollen but not in pollen leachate. Dissociation-reassociation experiments reveal that the set II bands are heterodimers involving, in part, the enzymes involved in the set I bands. These data combined with those from full-sib progeny analysis lead us to propose a three-locus model to explain the TPI isozyme banding patterns in cherimoya. Sets I and IV consist of the allelic products of individual, single loci. Sets I and II occur in the cytoplasm. Set IV occurs in organelles. Set II isozymes are the intergenic heterodimers of the locus coding for set I and the locus coding for set III. Our results reported here are contrasted with the TPI isozyme patterns known for other vascular plants and suggest that the locus coding for set III may be a duplication of very ancient origin.
对种子植物中磷酸丙糖异构酶（TPI）同工酶的详细解读仅限于少数物种。在番荔枝（一种原始被子植物）中经常观察到三组TPI条带。最慢的I组表现为一条或三条条带；第二慢的II组为一条或两条条带；最快的IV组为一条或三条条带。在IV组条带正阴极处有一组微弱的III组条带，只有过度染色时才很少被检测到。IV组条带在研磨提取的花粉中表达，但在花粉渗滤液中不表达。解离-重结合实验表明，II组条带是异二聚体，部分涉及I组条带中的酶。这些数据与全同胞后代分析的数据相结合，使我们提出了一个三位点模型来解释番荔枝中TPI同工酶的条带模式。I组和IV组由单个单一位点的等位基因产物组成。I组和II组出现在细胞质中。IV组出现在细胞器中。II组同工酶是编码I组的位点和编码III组的位点之间的基因间异二聚体。我们在此报告的结果与其他维管植物已知的TPI同工酶模式形成对比，表明编码III组的位点可能是非常古老起源的重复。
