Implicated in the regulation of RB1 expression. Functions as a DNA-binding transcription factor. Is a potent regulator of the RB1 pathway and a mediator that plays a crucial role in muscular differentiation. Expression is, thus, a prerequisite for myogenic differentiation. Involved in autophagy. Required for autophagosome formation (By similarity). Inhibits PTK2/FAK1 and PTK2B/PYK2 activity and activation of downstream signaling pathways.
Expression levels correlated closely with those of RB1 in cancer cell lines as well as in various normal human tissues. Abundantly expressed in human musculoskeletal and cultured osteosarcoma cells.
Expression was difficult to detect in immature proliferating chondroblasts or myogenic cells in embryos, but became obvious and prominent concomitantly with the maturation of osteocytes, chondrocytes, and skeletal muscle cells. Expression in these musculoskeletal cells increased with RB1 expression, which is linked to the terminal differentiation of many tissues and cells. The introduction of the wild-type protein decreased the formation of macroscopic colonies in a cell growth assay.
Nucleus. Cytoplasm > cytosol. Preautophagosomal structure. Under starvation conditions, is localized to puncate structures primarily representing the isolation membrane that sequesters a portion of the cytoplasm resulting in the formation of an autophagosome.