Abstract
Sulfation is a Golgi-specific modification of secretory proteins. We have characterized the proteins that are labeled with 35SO4 in cultures of rat hepatocytes and studied their transport to the medium. Analysis by polyacrylamide gel electrophoresis showed that of the five most heavily labeled proteins, four had well-defined mobilities--apparent molecular masses of 188, 142, 125, and 82 kDa--whereas one was electrophoretically heterogeneous--apparent molecular mass of 35-45 kDa. Judging by their relatively high resistance to acid treatment, the sulfate residues in the 125- and 35-45-kDa proteins were linked to carbohydrate. Some of the secreted proteins were sialylated. In samples of pulse-labeled cells, there appeared to be no unsialylated forms, indicating that sulfation occurred after sialylation, presumably in the trans Golgi. Kinetic experiments showed that the cellular half-life was the same for all the sulfated proteins--about 8 min--consistent with the idea that transport from the Golgi complex to the cell surface occurs by liquid bulk flow.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.