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Updated: Mar 1, 2026

Studying Protein Import into Chloroplasts Using Protoplasts
Published on: December 10, 2018
HP30-2, a mitochondrial PRAT protein for import of signal sequence-less precursor proteins in Arabidopsis thaliana
Claudia Rossig1, John Gray2, Oscar Valdes1
1Laboratory of Plant Molecular Genetics and Laboratory of Environmental and Systems Biology, Grenoble-Alpes-University, Grenoble, France.
Abstract:
Chloroplasts and mitochondria contain a family of putative preprotein and amino acid transporters designated PRAT. Here, we analyzed the role of two previously characterized PRAT protein family members, encoded by At3g49560 (HP30) and At5g24650 (HP30-2), in planta using a combination of genetic, cell biological and biochemical approaches. Expression studies and green fluorescent protein tagging identified HP30-2 both in chloroplasts and mitochondria, whereas HP30 was located exclusively in chloroplasts. Biochemical evidence was obtained for an association of mitochondrial HP30-2 with two distinct protein complexes, one containing the inner membrane translocase TIM22 and the other containing an alternative NAD(P)H dehydrogenase subunit (NDC1) implicated in a respiratory complex 1-like electron transport chain. Through its association with TIM22, HP30-2 is involved in the uptake of carrier proteins and other, hydrophobic membrane proteins lacking cleavable NH2 -terminal presequences, whereas HP30-2's interaction with NDC1 may permit controlling mitochondrial biogenesis and activity.
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