N-Oct 5 is generated by in vitro proteolysis of the neural POU-domain protein N-Oct 3.
The neural POU-domain proteins N-Oct 3 and N-Oct 5 were first identified in electrophoretic mobility retardation assays through their ability to bind to the octamer sequence ATGCAAAT. These two N-Oct factors are detected in extracts from tumor-derived and normal neural cells. They are present differentially, however, in extracts from melanocytes and melanoma cells: N-Oct 3 is present in extracts from both melanocytes and melanoma cells, whereas N-Oct 5 is more evident in extracts from metastatic melanoma cells. We show here that a cDNA encoding N-Oct 3 directs synthesis of both the N-Oct 3 and N-Oct 5 proteins and that the N-Oct 5 protein in neural and melanoma-cell extracts is also related to N-Oct 3. N-Oct 5, however, is apparently not expressed in vivo: It is not detected if cells are rapidly lysed in SDS or if extracts are prepared with a cocktail of protease inhibitors that includes the serine-protease inhibitor 4-(2-Aminoethyl)benzenesulfonyl fluoride hydrochloride (AEBSF). These data suggest that N-Oct 5 is a specific in vitro proteolytic cleavage product of N-Oct 3 and is not directly related to melanocyte malignancy.
Atanasoski
S
S
Cold Spring Harbor Laboratory, New York 11724, USA.
Schreiber
E
E
Fontana
A
A
Herr
W
W
D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D019556:COS Cells; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D018076:DNA, Complementary; D018398:Homeodomain Proteins; D006801:Humans; D006868:Hydrolysis; D008545:Melanoma / Q000235:genetics / Q000473:pathology; D050809:POU Domain Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D018398:Homeodomain Proteins; D050809:POU Domain Factors; D014157:Transcription Factors; C085076:transcription factor Brn-2