Cultured human melanoma cells biosynthesize a novel form of laminin that lacks the M/sub r/ = 400 kDa subunit
A human melanoma cell line (A375) was found to produce an unusual type of laminin composed exclusively of M/sub r/ = 200 kDa B subunits and lacking the M/sub r/ = 400 kDa A subunit. Detergent lysates of A375 cells pulsed with (/sup 35/S)methionine contained an immunoreactive form of laminin that migrated on nonreduced SDS-PAGE with an apparent M/sub r/ = 850 kDa. The 850 kDa laminin was clearly resolved from the typical M/sub r/ = 950 kDa laminin composed of A and B subunit types that is produced by a variety of cultured cells such as human choriocarcinoma (JAR) cells. Upon reduction of the intersubunit disulfide bonds of the A375 laminin, a pair of polypeptides co-migrated on SDS-PAGE with the M/sub r/ = 200 kDa B subunit doublet of JAR laminin. The A-deficient A375 laminin does not seem to be a result of the proteolysis of A subunit in cell lysates. No degradation of (/sup 35/S)methionine-labeled JAR laminin was observed upon incubation with nonradioactive A375 cell lysate supplemented in the usual manner with ten protease inhibitors. Furthermore, A subunit did not appear transiently in A375 cells at any chase time (0-4 hr) following a 10-min biosynthetic pulse with (/sup 35/S)methionine. The authors observations suggest that A375 cells biosynthesize principally the B subunits of laminin and assemble them to form a disulfide-linked macromolecule, possibly a B/sub 4/ tetramer.
- Research Organization:
- Univ. of Michigan Medical School, Ann Arbor
- OSTI ID:
- 6278263
- Report Number(s):
- CONF-870644-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Vol. 46:6; ISSN FEPRA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOSYNTHESIS
CARBOXYLIC ACIDS
CELL CULTURES
DAYS LIVING RADIOISOTOPES
DISEASES
DRUGS
ELECTROPHORESIS
EVEN-ODD NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
MAN
MELANOMAS
METHIONINE
NEOPLASMS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PRIMATES
PROTEINS
RADIOISOTOPES
SULFUR 35
SULFUR ISOTOPES
SYNTHESIS
TRACER TECHNIQUES
TUMOR CELLS
VERTEBRATES