Dibley Marris G, Ryan Michael T, Stroud David A
Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Australia.
FEBS Lett. 2017 Jan;591(1):109-117. doi: 10.1002/1873-3468.12527. Epub 2016 Dec 30.
Human mitochondrial complex I is the first enzyme of the mitochondrial respiratory chain. Complex I is composed of 45 subunits, seven encoded by mitochondrial DNA, while the remainder are encoded by nuclear DNA. All nuclear-encoded subunits are thought to be expressed as a single isoform. Here we reveal subunit NDUFV3 to be present in both the canonical 10 kDa and a novel 50 kDa isoform, generated through alternative splicing. Both isoforms assemble into complex I and their levels vary in different tissues. While the 50 kDa isoform appears to be dominant in HEK293T cells, we find either isoform alone is sufficient for assembly of mature complex I. NDUFV3 represents the first known complex I subunit present in two functional isoforms.
人类线粒体复合体I是线粒体呼吸链的首个酶。复合体I由45个亚基组成，其中7个由线粒体DNA编码，其余则由核DNA编码。所有核编码亚基被认为以单一异构体形式表达。在此我们揭示亚基NDUFV3以经典的10 kDa和通过可变剪接产生的新型50 kDa异构体两种形式存在。两种异构体均组装入复合体I，且它们在不同组织中的水平有所不同。虽然50 kDa异构体在HEK293T细胞中似乎占主导，但我们发现单独任何一种异构体都足以组装成熟的复合体I。NDUFV3是首个已知的以两种功能异构体形式存在的复合体I亚基。
