In:
Journal of Cell Science, The Company of Biologists, Vol. 109, No. 4 ( 1996-04-01), p. 805-815
Abstract:
We found by using a 45Ca2+ overlay technique a large amount of Ca2+-binding activity in bovine amniotic fluid from which a novel calcium-binding protein (CaBP) was purified and is referred to as CAAF1 (calcium-binding protein in amniotic fluid-1), with an apparent molecular mass of 8 kDa determined by N-tris(hydroxymethyl)methylglycine/SDS-PAGE. It was structurally homolo gous with MRP/calgranulin proteins (MRP8/calgranulin A and MRP14/calgranulin B), members of the S100 protein family, which are abundantly found in the cytoplasm of granulocytes and macrophages. CAAF1 lacked the predicted signal peptide sequence, which is consistent with other CaBPs. The tissue and cellular dis tribution of CAAF1 was determined by monoclonal anti bodies developed against this protein. Its immunoreactiv ity was found in squamous epithelial cells, neutrophils, and some macrophages throughout the fetal body. An especially characteristic staining pattern was obtained in the squamous epithelium, including that of the esophagus, skin and amnion: CAAF1 was detected in the suprabasal squamous epithelial cells undergoing differentiation, but not in the cells in the proliferating basal layer. Northern blot analysis also showed that CAAF1 mRNA was highly expressed in bovine fetal esophagus and skin. On the other hand, our ELISA studies showed that CAAF1 protein was present in amniotic fluid at a concentration of about 120 nM, which was over 30 times as high as that in the fetal serum. These results suggested that CAAF1 is one of the stage-specific proteins in the differentiation of squamous epithelial cells, and that CAAF1 is preferen tially produced by fetal squamous epithelial cells, including epidermal keratinocytes and amniotic epithelial cells, and it is stored in the amniotic fluid during embryo genesis.
Type of Medium:
Online Resource
ISSN:
0021-9533
,
1477-9137
DOI:
10.1242/jcs.109.4.805
Language:
English
Publisher:
The Company of Biologists
Publication Date:
1996
detail.hit.zdb_id:
219171-4
detail.hit.zdb_id:
1483099-1
SSG:
12
