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

Journal Article · Fri Nov 01 04:00:00 EST 1991 · Experimental Cell Research; (United States)

DOI:https://doi.org/10.1016/0014-4827(91)90488-G· OSTI ID:5312624

Melhus, H; Rask, L ^[1]; Nilsson, T; Peterson, P A ^[2]

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1. Uppsala Univ. (Sweden) Swedish Univ. of Agricultural Sciences, Uppsala (Sweden)
2. Research Inst. of Scripps Clinic, La Jolla, CA (United States)

To establish a suitable experimental system for studies of the interaction of retinol-binding protein (RBP) with transthyretin (TTR) the authors 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 from a complex with RBP in the ER. The data suggest that RBP and TTR are secreted as a complex.

• OSTI ID: 5312624
• Journal Information: Experimental Cell Research; (United States), Journal Name: Experimental Cell Research; (United States) Vol. 197:1; ISSN ECREA; ISSN 0014-4827
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
BIOCHEMISTRY
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMISTRY
DNA
ENDOPLASMIC RETICULUM
GENE REGULATION
HELA CELLS
HORMONES
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
PEPTIDE HORMONES
PROTEINS
RECOMBINANT DNA
THYROID HORMONES
THYROXINE
TRANSCRIPTION
VITAMIN A
VITAMINS