Retinol-binding protein and transthyretin expressed in HeLa cells form a complex in the endoplasmic reticulum in both the absence and the presence of retinol
1991 (English)In: Experimental Cell Research, ISSN 0014-4827, Vol. 197, no 1, 119-124 p.Article in journal (Refereed) Published
To establish a suitable experimental system for studies of the interaction of retinol-binding protein (RBP) with transthyretin (TTR) we have expressed the corresponding cDNAs in HeLa cells. To investigate whether complex formation might occur already in the endoplasmic reticulum (ER), the C-terminal ER retention signal, KDEL, was attached to TTR. The tetrameric TTR-KDEL fusion protein was retained in the ER of HeLa cells. When RBP was co-expressed with TTR-KDEL, RBP was retained intracellularly. A cDNA-encoding purpurin, a protein which is 50% identical to RBP, was then expressed together with TTR-KDEL. Purpurin was not retained intracellularly and did not bind to TTR coupled to Sepharose. The effect of the vitamin A status on the secretion of TTR and RBP was examined. While TTR expressed alone was not retained intracellularly, TTR was retained in vitamin A-deficient cells when co-expressed with RBP. Addition of retinol stimulated rapid secretion of both proteins. These results demonstrate that TTR can form a complex with RBP in the ER. The data suggest that RBP and TTR are secreted as a complex.
Place, publisher, year, edition, pages
1991. Vol. 197, no 1, 119-124 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-54905DOI: 10.1016/0014-4827(91)90488-GPubMedID: 1915658OAI: oai:DiVA.org:uu-54905DiVA: diva2:82814