Journal Article

Expression and Characterization of a Very Low Density Lipoprotein Receptor Variant Lacking the O-Linked Sugar Region Generated by Alternative Splicing

Hiroaki Iijima, Masaaki Miyazawa, Juro Sakai, Kenta Magoori, Mitsuko R. Ito, Hiroyuki Suzuki, Masato Nose, Yutaka Kawarabayasi and Tokuo T. Yamamoto

in The Journal of Biochemistry

Published on behalf of The Japanese Biochemical Society

Volume 124, issue 4, pages 747-755
Published in print October 1998 | ISSN: 0021-924X
Published online October 1998 | e-ISSN: 1756-2651 | DOI: https://dx.doi.org/10.1093/oxfordjournals.jbchem.a022175

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The very low density lipoprotein receptor (VLDLR) gene contains an exon encoding a region of clustered serine and threonine residues immediately outside the membrane-spanning sequence, and this region has been proposed to be the site of clustered O-linked carbohydrate chains. Two forms of VLDLR transcripts, with and without the O-linked sugar region, are generated through alternative splicing. Reverse transcription polymerase chain reaction with RNAs from various rabbit tissues revealed that the VLDLR transcript with the O-linked sugar region (type-1 VLDLR) is the major transcript in heart and muscle, while the VLDLR transcript without the O-linked sugar region (type-2 VLDLR) predominates in non-muscle tissues, including cerebrum, cerebellum, kidney, spleen, adrenal gland, testis, ovary, and uterus. Hamster fibroblasts expressing type-2 VLDLR bound with relatively low affinity to β-migrating very low density lipoprotein compared with type-1 VLDLR-transfected cells. In contrast, the internalization, dissociation, and degradation of the ligand were not significantly impaired in either type of VLDLR-transfected cell. The receptor proteins in type-2 VLDLR-transfected cells underwent rapid degradation and accumulated in the culture medium, while those in type-1 VLDLR-transfected cells were stable and resistant to proteolytic cleavage. Analysis of the O-linked sugars of both types of transfected cells suggested that the O-linked sugar region is the major site for O-glycosylation.

Keywords: lipoprotein; O-linked sugar; splicing variant; VLDL receptor

Journal Article.  0 words. 

Subjects: Biochemistry