Abstract
We have characterized the early biosynthetic forms of secretory component (SC). SC is synthesized in various glandular epithelial cells and functions in transepithelial transport of certain polymeric immunoglobulins. In rabbit, mature SC is known to be heterogeneous, consisting of two or three immunologically related glycoproteins. Using translation of mRNA from rabbit mammary gland or liver in a wheat germ cell-free system supplemented with dog pancreas microsomal vesicles, we discovered that the translation products of SC mRNA include at least four distinct polypeptides. Moreover, we found that all four polypeptides are synthesized not as soluble secretory forms but as considerably larger transmembrane forms that are core-glycosylated and asymmetrically integrated into the dog pancreas microsomal vesicles in a translation-coupled manner. We therefore conclude that the mature secreted forms of SC are endoproteolytic fragments derived from and comprising the ectoplasmic portion of the transmembrane precursor forms. The detection of transmembrane precursor forms for mature SC provides a protein structural basis for their function as receptors mediating transepithelial transport of immuno-globulin molecules.
Full text
PDF




Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Aviv H., Leder P. Purification of biologically active globin messenger RNA by chromatography on oligothymidylic acid-cellulose. Proc Natl Acad Sci U S A. 1972 Jun;69(6):1408–1412. doi: 10.1073/pnas.69.6.1408. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bielinska M., Boime I. mRNA-dependent synthesis of a glycosylated subunit of human chorionic gonadotropin in cell-free extracts derived from ascites tumor cells. Proc Natl Acad Sci U S A. 1978 Apr;75(4):1768–1772. doi: 10.1073/pnas.75.4.1768. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Blobel G. Intracellular protein topogenesis. Proc Natl Acad Sci U S A. 1980 Mar;77(3):1496–1500. doi: 10.1073/pnas.77.3.1496. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bonatti S., Blobel G. Absence of a cleavable signal sequence in Sindbis virus glycoprotein PE2. J Biol Chem. 1979 Dec 25;254(24):12261–12264. [PubMed] [Google Scholar]
- Bonatti S., Cancedda R., Blobel G. Membrane biogenesis. In vitro cleavage, core glycosylation, and integration into microsomal membranes of sindbis virus glycoproteins. J Cell Biol. 1979 Jan;80(1):219–224. doi: 10.1083/jcb.80.1.219. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bonner W. M., Laskey R. A. A film detection method for tritium-labelled proteins and nucleic acids in polyacrylamide gels. Eur J Biochem. 1974 Jul 1;46(1):83–88. doi: 10.1111/j.1432-1033.1974.tb03599.x. [DOI] [PubMed] [Google Scholar]
- Brandtzaeg P. Mucosal and glandular distribution of immunoglobulin components: differential localization of free and bound SC in secretory epithelial cells. J Immunol. 1974 Apr;112(4):1553–1559. [PubMed] [Google Scholar]
- Buell G. N., Wickens M. P., Payvar F., Schimke R. T. Synthesis of full length cDNAs from four partially purified oviduct mRNAs. J Biol Chem. 1978 Apr 10;253(7):2471–2482. [PubMed] [Google Scholar]
- Crago S. S., Kulhavy R., Prince S. J., Mestecky J. Secretory component of epithelial cells is a surface receptor for polymeric immunoglobulins. J Exp Med. 1978 Jun 1;147(6):1832–1837. doi: 10.1084/jem.147.6.1832. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hanover J. A., Lennarz W. J. N-Linked glycoprotein assembly. Evidence that oligosaccharide attachment occurs within the lumen of the endoplasmic reticulum. J Biol Chem. 1980 Apr 25;255(8):3600–3604. [PubMed] [Google Scholar]
- Katz F. N., Rothman J. E., Lingappa V. R., Blobel G., Lodish H. F. Membrane assembly in vitro: synthesis, glycosylation, and asymmetric insertion of a transmembrane protein. Proc Natl Acad Sci U S A. 1977 Aug;74(8):3278–3282. doi: 10.1073/pnas.74.8.3278. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Knight K. L., Rosenzweig M., Lichter E. A., Hanly W. C. Rabbit secretory IgA: identification and genetic control of two allotypes of secretory component. J Immunol. 1974 Mar;112(3):877–882. [PubMed] [Google Scholar]
- Kraehenbuhl J. P., Racine L., Galardy R. E. Localization of secretory IgA, secretory component, and alpha chain in the mammary gland of lactating rabbits by immunoelectron microscopy. Ann N Y Acad Sci. 1975 Jun 30;254:190–202. doi: 10.1111/j.1749-6632.1975.tb29169.x. [DOI] [PubMed] [Google Scholar]
- Kühn L. C., Kraehenbuhl J. P. Interaction of rabbit secretory component with rabbit IgA dimer. J Biol Chem. 1979 Nov 10;254(21):11066–11071. [PubMed] [Google Scholar]
- Kühn L. C., Kraehenbuhl J. P. Role of secretory component, a secreted glycoprotein, in the specific uptake of IgA dimer by epithelial cells. J Biol Chem. 1979 Nov 10;254(21):11072–11081. [PubMed] [Google Scholar]
- Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
- Lingappa V. R., Katz F. N., Lodish H. F., Blobel G. A signal sequence for the insertion of a transmembrane glycoprotein. Similarities to the signals of secretory proteins in primary structure and function. J Biol Chem. 1978 Dec 25;253(24):8667–8670. [PubMed] [Google Scholar]
- Lingappa V. R., Lingappa J. R., Prasad R., Ebner K. E., Blobel G. Coupled cell-free synthesis, segregation, and core glycosylation of a secretory protein. Proc Natl Acad Sci U S A. 1978 May;75(5):2338–2342. doi: 10.1073/pnas.75.5.2338. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nagura H., Nakane P. K., Brown W. R. Translocation of dimeric IgA through neoplastic colon cells in vitro. J Immunol. 1979 Nov;123(5):2359–2368. [PubMed] [Google Scholar]
- Orlans E., Peppard J., Fry J. F., Hinton R. H., Mullock B. M. Secretory component as the receptor for polymeric IgA on rat hepatocytes. J Exp Med. 1979 Dec 1;150(6):1577–1581. doi: 10.1084/jem.150.6.1577. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Poger M. E., Lamm M. E. Localization of free and bound secretory component in human intestinal epithelial cells. A model for the assembly of secretory IgA. J Exp Med. 1974 Mar 1;139(3):629–642. doi: 10.1084/jem.139.3.629. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Renston R. H., Jones A. L., Christiansen W. D., Hradek G. T., Underdown B. J. Evidence for a vesicular transport mechanism in hepatocytes for biliary secretion of immunoglobulin A. Science. 1980 Jun 13;208(4449):1276–1278. doi: 10.1126/science.7375938. [DOI] [PubMed] [Google Scholar]
- Shields D., Blobel G. Cell-free synthesis of fish preproinsulin, and processing by heterologous mammalian microsomal membranes. Proc Natl Acad Sci U S A. 1977 May;74(5):2059–2063. doi: 10.1073/pnas.74.5.2059. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shields D., Blobel G. Efficient cleavage and segregation of nascent presecretory proteins in a reticulocyte lysate supplemented with microsomal membranes. J Biol Chem. 1978 Jun 10;253(11):3753–3756. [PubMed] [Google Scholar]
- Socken D. J., Jeejeebhoy K. N., Bazin H., Underdown B. J. Identification of secretory component as an IgA receptor on rat hepatocytes. J Exp Med. 1979 Dec 1;150(6):1538–1548. doi: 10.1084/jem.150.6.1538. [DOI] [PMC free article] [PubMed] [Google Scholar]
- South M. A., Cooper M. D., Wollheim F. A., Hong R., Good R. A. The IgA system. I. Studies of the transport and immunochemistry of IgA in the saliva. J Exp Med. 1966 Apr 1;123(4):615–627. doi: 10.1084/jem.123.4.615. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Toneguzzo F., Ghosh H. P. Synthesis and glycosylation in vitro of glycoprotein of vesicular stomatitis virus. Proc Natl Acad Sci U S A. 1977 Apr;74(4):1516–1520. doi: 10.1073/pnas.74.4.1516. [DOI] [PMC free article] [PubMed] [Google Scholar]





