Characterization of three human sec14p-like proteins: alpha-tocopherol transport activity and expression pattern in tissues.
Three closely related human sec14p-like proteins (hTAP1, 2, and 3, or SEC14L2, 3, and 4, respectively) have been described. These proteins may participate in intracellular lipid transport (phospholipids, squalene, tocopherol analogues and derivatives) or influence regulatory lipid-dependent events. Here, we show that the three recombinant hTAP proteins associate with the Golgi apparatus and mitochondria, and enhance the in vitro transport of radioactively labeled alpha-tocopherol to mitochondria in the same order of magnitude as the human alpha-tocopherol transfer protein (alpha-TTP). hTAP1 and hTAP2 are expressed in several cell lines, whereas the expression level of hTAP3 is low. Expression of hTAP1 is induced in human umbilical cord blood-derived mast cells upon differentiation by interleukin 4. In tissues, the three hTAPs are detectable ubiquitously at low level; pronounced and localized expression is found for hTAP2 and hTAP3 in the perinuclear region in cerebellum, lung, liver and adrenal gland. hTAP3 is well expressed in the epithelial duct cells of several glands, in ovary in endothelial cells of small arteries as well as in granulosa and thecal cells, and in testis in Leydig cells. Thus, the three hTAPs may mediate lipid uptake, secretion, presentation, and sub-cellular localization in a tissue-specific manner, possibly using organelle- and enzyme-specific docking sites.
Zingg
Jean-Marc
JM
Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland. zin34@swissonline.ch
Kempna
Petra
P
Paris
Marcel
M
Reiter
Elke
E
Villacorta
Luis
L
Cipollone
Rita
R
Munteanu
Adelina
A
De Pascale
Clara
C
Menini
Stefano
S
Cueff
Alexandra
A
Arock
Michel
M
Azzi
Angelo
A
Ricciarelli
Roberta
R
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D001692:Biological Transport; D045744:Cell Line, Tumor; D006801:Humans; D015847:Interleukin-4 / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014018:Tissue Distribution; D024502:alpha-Tocopherol / Q000378:metabolism*
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; D010446:Peptide Fragments; D011498:Protein Precursors; D011994:Recombinant Proteins; C073119:TAP1 protein, human; C405036:thyrotropin-releasing hormone-associated peptide 3, human; C071692:TAP2 protein, human; D015847:Interleukin-4; D024502:alpha-Tocopherol