Entactin-2: a new member of basement membrane protein with high homology to entactin/nidogen.
Using the new signal sequence trap (SST) method, we isolated several clones encoding secreted and transmembrane proteins from KUSA cells, a murine osteoblast-like cell line. One isolated novel clone, termed entactin-2, exhibited a high similarity to mouse entactin/nidogen, a basement membrane protein. Although deduction of the amino acid sequence of entactin-2 revealed only 27.4% homology to entactin, many structural similarities were seen between both proteins. Entactin-2 contains five EGF-like and two thyroglobulin-like motifs, which are both cysteine-rich. Comparison of both proteins clearly revealed that entactin-2 also contains related domain structures. The rod-like domain of entactin-2, containing the RGD integrin recognition sequence, fused to glutathione-S transferase (GST), revealed a cell surface-binding activity similar to that of entactin. In addition, the tissue distribution of entactin-2 mRNA resembled that of entactin. Furthermore, mRNA expression of both genes decreased as osteoblastic differentiation progressed. These results suggest that entactin-2 is a member of the entactin gene family, may have entactin-related functions, and might act as a basement membrane component.
Kimura
N
N
Gene Search Program, Chugai Research Institute for Molecular Medicine, Ibaraki, Japan.
Toyoshima
T
T
Kojima
T
T
Shimane
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001485:Basement Membrane / Q000737:chemistry; D002135:Calcium-Binding Proteins; D015815:Cell Adhesion Molecules; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005057:Eukaryotic Cells / Q000378:metabolism; D015870:Gene Expression / Q000235:genetics; D005796:Genes / Q000235:genetics; D008562:Membrane Glycoproteins / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D016415:Sequence Alignment; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D002135:Calcium-Binding Proteins; D015815:Cell Adhesion Molecules; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C112846:Nid2 protein, mouse; C029967:nidogen