Centre for Plant Sciences, Irene Manton Building, University of Leeds, Leeds LS2 9JT, UK.
FEBS Lett. 2012 Jul 30;586(16):2280-6. doi: 10.1016/j.febslet.2012.05.065. Epub 2012 Jun 16.
Peroxisomal ABC transporters of animals and fungi are "half-size" proteins which dimerise to form a functional transporter. However, peroxisomal ABC transporters of land plants are synthesised as a single polypeptide which represents a fused heterodimer. The N- and C-terminal pseudo-halves of COMATOSE (CTS; AtABCD1) were expressed as separate polypeptides which bound Pex19 in vitro and targeted independently to the peroxisome membrane in yeast, where they were stable but not functional. When co-expressed, the pseudo-halves were fully functional as indicated by ATPase activity and rescue of the pxa1pxa2Δ mutant for growth on oleate. The functional significance of heterodimer asymmetry is discussed.
动物和真菌的过氧化物酶体 ABC 转运蛋白是“半大小”的蛋白质，它们二聚化形成功能性转运蛋白。然而，陆地植物的过氧化物酶体 ABC 转运蛋白是作为单一多肽合成的，代表融合的异二聚体。COMATOSE（CTS；AtABCD1）的 N-和 C-末端假半胱氨酸被表达为单独的多肽，这些多肽在体外与 Pex19 结合，并在酵母中独立靶向过氧化物酶体膜，在酵母中它们是稳定的，但没有功能。当共表达时，假半胱氨酸具有完全的功能，如 ATP 酶活性所示，并拯救了 pxa1pxa2Δ 突变体在油酸上的生长。异二聚体不对称性的功能意义正在讨论中。
