Membrane secretory component is cleaved on the cell surface of rat hepatocytes

Conference · Tue Mar 04 23:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:6798691

Musil, L S; Baenziger, J U

Transcellular transport of polymeric IgA from serum to bile by rat hepatocytes is mediated by a 105Kd membranous form of secretory component (mSC). In the presence or absence of IgA, mSC is cleaved and released into bile as a soluble 80Kd protein (fSC). They used monolayer cultures of rat hepatocytes, which synthesize mSC and efficiently cleave it to fSC, to determine the site of this conversion. (/sup 35/S)Cys-mSC accumulated in hepatocytes in the presence of leupeptin and was released as fSC when hepatocytes were placed in leupeptin-free media at 37/sup 0/. Small amounts of fSC were also produced when leupeptin was removed at 4/sup 0/, suggesting cleavage might occur on the cell membrane. Lactoperoxidase-catalyzed iodination of hepatocytes at 4/sup 0/ selectively labeled surface mSC which remained trypsin sensitive at 4/sup 0/. Hepatocytes maintained at 4/sup 0/ released significant amounts of /sup 125/I-mSC as fSC. Anti-SC antiserum reduced fSC generation at 4/sup 0/ by 70%. Following incubation at 37/sup 0/ for 10 min, /sup 125/I-mSC became resistant to degradation by trypsin and no production of fSC was seen if the cells were returned to 4/sup 0/. /sup 125/I-mSC was also cleaved to fSC following disruption by Dounce homogenization if cells were maintained at 4/sup 0/ following iodination but not if they were incubated at 37/sup 0/ for 10 min. They propose that mSC is cleaved to fSC at the plasma membrane but not intracellularly. This may reflect localization of the protease at the cell surface in a bile canalicular-like domain.

• Research Organization: Washington Univ. School of Medicine, St. Louis, MO
• OSTI ID: 6798691
• Report Number(s): CONF-8604222-
• Journal Information: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 45:4; ISSN FEPRA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BILE
BIOLOGICAL LOCALIZATION
BIOLOGICAL MATERIALS
BIOSYNTHESIS
BODY FLUIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHEMICAL REACTIONS
CLEAVAGE
CRYSTAL STRUCTURE
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
EVEN-ODD NUCLEI
GLOBULINS
HALOGENATION
IMMUNOGLOBULINS
INTERMEDIATE MASS NUCLEI
IODINATION
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LIVER CELLS
MAMMALS
MATERIALS
MEMBRANES
MICROSTRUCTURE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PEROXIDASES
PROTEINS
RADIOISOTOPES
RATS
RODENTS
SOMATIC CELLS
SULFUR 35
SULFUR ISOTOPES
SYNTHESIS
TRACER TECHNIQUES
VERTEBRATES