Glucose-induced regulation of protein import receptor tom22 by cytosolic and mitochondria-bound kinases

Carolin Gerbeth, Oliver Schmidt, Sanjana Rao, Angelika B. Harbauer, Despina Mikropoulou, Magdalena Opalinska, Bernard Guiard, Nikolaus Pfanner, Chris Meisinger

Research output: Contribution to journalArticlepeer-review

82 Scopus citations

Abstract

SUMMARY Most mitochondrial proteins are imported by the translocase of the outer mitochondrial membrane (TOM). Tom22 functions as central receptor and transfers preproteins to the import pore. Casein kinase 2 (CK2) constitutively phosphorylates the cytosolic precursor of Tom22 at Ser44 and Ser46 and, thus, promotes its import. It is unknown whether Tom22 is regulated under different metabolic conditions. We report that CK1, which is involved in glucose-induced signal transduction, is bound to mitochondria. CK1 phosphorylates Tom22 at Thr57 and stimulates the assembly of Tom22 and Tom20. In contrast, protein kinase A (PKA), which is also activated by the addition of glucose, phosphorylates the precursor of Tom22 at Thr76 and impairs its import. Thus, PKA functions in an opposite manner to CK1 and CK2. Our results reveal that three kinases regulate the import and assembly of Tom22, demonstrating that the central receptor is a major target for the posttranslational regulation of mitochondrial protein import.

Original languageEnglish
Pages (from-to)578-587
Number of pages10
JournalCell Metabolism
Volume18
Issue number4
DOIs
StatePublished - 1 Oct 2013
Externally publishedYes

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