BRCA1 is secreted and exhibits properties of a granin.

Germline mutations in BRCA1 are responsible for most cases of inherited breast and ovarian cancer . However, the function of the BRCA1 protein has remained elusive.
We now show that BRCA1 encodes a 190-kD protein with sequence homology and biochemical analogy to the granin protein family.
Interestingly, BRCA2 also includes a motif similar to the granin consensus at the C terminus of the protein.
Both BRCA1 and the granins localize to secretory vesicles, are secreted by a regulated pathway, are post-translationally glycosylated and are responsive to hormones.
As a regulated secretory protein, BRCA1 appears to function by a mechanism not previously described for tumour suppressor gene products.. 
