| First Author | Lamhonwah AM | Year | 2006 |
| Journal | Biochem Biophys Res Commun | Volume | 345 |
| Issue | 4 | Pages | 1315-25 |
| PubMed ID | 16729965 | Mgi Jnum | J:109656 |
| Mgi Id | MGI:3629436 | Doi | 10.1016/j.bbrc.2006.05.026 |
| Citation | Lamhonwah AM, et al. (2006) Novel localization of OCTN1, an organic cation/carnitine transporter, to mammalian mitochondria. Biochem Biophys Res Commun 345(4):1315-25 |
| abstractText | Carnitine is a zwitterion essential for the beta-oxidation of fatty acids. We report novel localization of the organic cation/carnitine transporter, OCTN1, to mitochondria. We made GFP- and RFP-human OCTN1 cDNA constructs and showed expression of hOCTN1 in several transfected mammalian cell lines. Immunostaining of GFP-hOCTN1 transfected cells with different intracellular markers and confocal fluorescent microscopy demonstrated mitochondrial expression of OCTN1. There was striking co-localization of an RFP-hOCTN1 fusion protein and a mitochondrial-GFP marker construct in transfected MEF-3T3 and no co-localization of GFP-hOCTN1 in transfected human skin fibroblasts with other intracellular markers. l-[(3)H]Carnitine uptake in freshly isolated mitochondria of GFP-hOCTN1 transfected HepG2 demonstrated a K(m) of 422muM and Western blot with an anti-GFP antibody identified the expected GFP-hOCTN1 fusion protein (90kDa). We showed endogenous expression of native OCTN1 in HepG2 mitochondria with anti-GST-hOCTN1 antibody. Further, we definitively confirmed intact l-[(3)H]carnitine uptake (K(m) 1324muM), solely attributable to OCTN1, in isolated mitochondria of mutant human skin fibroblasts having <1% of carnitine acylcarnitine translocase activity (alternate mitochondrial carnitine transporter). This mitochondrial localization was confirmed by TEM of murine heart incubated with highly specific rabbit anti-GST-hOCTN1 antibody and immunogold labeled goat anti-rabbit antibody. This suggests an important yet different role for OCTN1 from other OCTN family members in intracellular carnitine homeostasis. |
