CA125 (also symbolized M17S2) is a tumor antigen widely used in monitoring ovarian cancer, although the nature of
the antigen is poorly understood.
NCBI Summary:
The protein encoded by this gene has been identified as an ovarian tumor antigen used in monitoring ovarian cancer. This protein contains a B-box/coiled coil motif, which is present in many genes with transformation potential. The function of this gene is unknown. This gene is located on a region of chromosome 17q21.1 that is in close proximity to tumor suppressor gene BRCA1. Three alternatively spliced variants are described.
General function
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Cellular localization
Plasma membrane
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Ovarian function
ovarian cancer
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Yin BW, et al 2001 reported the molecular cloning of the CA125 ovarian cancer antigen:
Identification as a new mucin (MUC16).
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CA125 is an ovarian cancer antigen that is basis for a widely-used serum assay
for the monitoring of patients with ovarian cancer, however detailed information
on its biochemical and molecular nature is lacking. The authors report the isolation of
a long, but partial, cDNA that corresponds to the CA125 antigen. A rabbit
polyclonal antibody produced to purified CA125 antigen was used to screen a
lambdaZAP cDNA library from OVCAR-3 cells in Escherichia coli. The longest
insert from the 54 positive isolated clones had a 5965 b.p. sequence containing a
stop codon and a poly A sequence but no clear 5' initiation sequence. The deduced
amino acid sequence has many of the attributes of a mucin molecule and was
designated CA125/MUC16 (gene symbol MUC16). These features include a high
serine, threonine, and proline content in an N-terminal region of nine partially
conserved tandem repeats (156 amino acids each) and a C-terminal region
non-tandem repeat sequence containing a possible transmembrane region and a
potential tyrosine phosphorylation site. Northern blotting showed that the level of
MUC16 mRNA correlated with the expression of CA125 in a panel of cell lines.