Recombinant Tarsius syrichta NADH-ubiquinone oxidoreductase chain 4 (MT-ND4)

Basic Research Questions

• What is MT-ND4 and what is its function in mitochondrial respiration?

  MT-ND4 (NADH-ubiquinone oxidoreductase chain 4) is a mitochondrial DNA-encoded subunit of Complex I in the respiratory chain. It plays a crucial role in electron transfer from NADH to ubiquinone and contributes to proton pumping across the inner mitochondrial membrane.

  Functionally, MT-ND4 is involved in:

  • NADH oxidation and ubiquinone reduction

  • Proton translocation across the inner mitochondrial membrane

  • Energy conservation as part of the oxidative phosphorylation system

  Mammalian mitochondrial Complex I consists of 45 subunits, including 7 mtDNA-encoded subunits (ND1, ND2, ND3, ND4, ND5, ND6, and ND4L). These mitochondrial-encoded components are integral to the membrane domain of the complex and are directly involved in proton pumping .

• What is the evolutionary significance of studying MT-ND4 from Tarsius syrichta?

  Studying MT-ND4 from the Philippine tarsier (Tarsius syrichta) has significant evolutionary implications:

  • Tarsiers occupy a unique phylogenetic position within primates, with ongoing debate about whether they should be grouped with strepsirrhine primates in a prosimian clade or with anthropoids in a haplorrhine clade

  • Genomic analysis involving 1.26 million base pair alignments from 1078 orthologous genes provides strong support for tarsiers belonging to the haplorrhine clade

  • MT-ND4 and other mitochondrial genes (12S, CytB, ND2) have been used for phylogeographic analysis of Tarsius syrichta lineages

  • Conservation genetics studies of Philippine tarsiers have revealed distinct evolutionary lineages within the species based in part on mitochondrial gene analysis

  Mitochondrial gene comparisons provide valuable data for resolving deep nodes in primate phylogeny, with divergence estimates suggesting evolutionary timescales for the separation of different primate lineages .

• How can recombinant MT-ND4 be properly stored and handled?

  Proper storage and handling of recombinant MT-ND4 protein is crucial for maintaining its stability and functionality:

  Storage Conditions:

  • Store at -20°C for regular storage

  • For extended storage, conserve at -20°C or -80°C

  • Working aliquots can be stored at 4°C for up to one week

  Buffer Composition:

  • Typically supplied in Tris-based buffer with 50% glycerol optimized for the protein

  Handling Recommendations:

  • Avoid repeated freezing and thawing cycles

  • Prepare small working aliquots to minimize freeze-thaw events

  • When designing experiments, consider the stability profile of the protein under various experimental conditions

  Experimental Considerations:

  • When incorporating the recombinant protein into functional assays, consider the presence of the tag (which is determined during the production process)

  • The protein's activity can be significantly affected by the absence of phospholipids, as observed in other NADH:ubiquinone oxidoreductase complexes

Advanced Research Questions