Novel secretory proline-rich proteoglycans from rat parotid. Cloning and characterization by expression in AtT-20 cells.
We have isolated two cDNAs that encode backbones of proline-rich proteoglycans identified previously in parotids of isoproterenol-treated rats (Blair, A. E., Castle, A. M., and Castle, J. D. (1991) Am. J. Physiol. 30, C897-C905). The sequences and domain structure of these cDNAs are characteristic of acidic proline-rich proteins, and potential glycosaminoglycan attachment sites are present within the acidic N-terminal domain. When the cDNAs were individually expressed in a mouse pituitary cell line, AtT-20, the expressed proteins were modified to sulfated proteoglycans. As in parotid acinar cells, only a fraction of the larger backbone (M(r) = 38,000) is modified by glycosaminoglycan addition; however, most of the smaller backbone (M(r) = 30,000) appears modified. Both proteoglycans expressed in AtT-20 cells contain heparan sulfate and chondroitin sulfate, whereas the proteoglycan in parotid contained chondroitin sulfate exclusively. Both proteoglycans are targeted to the regulated secretory pathway in AtT-20 cells where they are stored more efficiently than a parotid basic proline-rich protein.
Department of Anatomy and Cell Biology, University of Virginia Health Sciences Center, Charlottesville 22908.
A M
AM
Castle
J D
JD
Castle
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA; D005455:Fluorescent Antibody Technique; D015723:Gene Library; D006025:Glycosaminoglycans / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D006027:Glycosides / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D010306:Parotid Gland / Q000378:metabolism*; D010452:Peptide Biosynthesis; D010455:Peptides / Q000235:genetics / Q000302:isolation & purification; D010902:Pituitary Gland; D055232:Proline-Rich Protein Domains; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid
D006025:Glycosaminoglycans; D006027:Glycosides; D009838:Oligodeoxyribonucleotides; D010455:Peptides; D011994:Recombinant Proteins; C010807:xylosides; D015124:8-Bromo Cyclic Adenosine Monophosphate; D004247:DNA