Oligomerization of the murine fatty acid transport protein 1.
The 63-kDa murine fatty acid transport protein 1 (FATP1) was cloned on the basis of its ability to augment fatty acid import when overexpressed in mammalian cells. The membrane topology of this integral plasma membrane protein does not resemble that of polytopic membrane transporters for other substrates. Western blot analysis of 3T3-L1 adipocytes that natively express FATP1 demonstrate a prominent 130-kDa species as well as the expected 63-kDa FATP1, suggesting that this protein may participate in a cell surface transport protein complex. To test whether FATP1 is capable of oligomerization, we expressed functional FATP1 molecules with different amino- or carboxyl-terminal epitope tags in fibroblasts. These epitope-tagged proteins also form apparent higher molecular weight species. We show that, when expressed in the same cells, differentially tagged FATP1 proteins co-immunoprecipitate. The region between amino acid residues 191 and 475 is sufficient for association of differentially tagged truncated FATP1 constructs. When wild type FATP1 and the non-functional s250a FATP1 mutant are co-expressed in COS7 cells, mutant FATP1 has dominant inhibitory function in fatty acid uptake assays. Taken together, these results are consistent with a model in which FATP1 homodimeric complexes play an important role in cellular fatty acid import.
Richards
M Rachel
MR
Center for Cardiovascular Research, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110-1010, USA.
Listenberger
Laura L
LL
Kelly
Alicia A
AA
Lewis
Sarah E
SE
Ory
Daniel S
DS
Schaffer
Jean E
JE
D016475:3T3 Cells; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000502:physiology; D019281:Dimerization; D050612:Fatty Acid Transport Proteins; D005227:Fatty Acids / Q000378:metabolism; D026901:Membrane Transport Proteins; D051379:Mice; D008970:Molecular Weight; D011233:Precipitin Tests
D002352:Carrier Proteins; D050612:Fatty Acid Transport Proteins; D005227:Fatty Acids; D026901:Membrane Transport Proteins; C493569:Slc27a1 protein, mouse; C493572:Slc27a4 protein, mouse