OCT4B1, a novel spliced variant of OCT4, generates a stable truncated protein with a potential role in stress response.

A novel variant of OCT4, OCT4B1, is highly expressed in pluripotent cells. OCT4B1 is also upregulated in various tumors and cell lines. Here, we have constructed a HA-tagged OCT4B1 construct, which could be translated into an N-terminally tagged protein, detectable by HA antibody. Western blotting revealed that OCT4B1 can act as a precursor for OCT4B, and it can also produce a truncated protein with a molecular size corresponding to that of predicted OCT4B1. Furthermore, our data demonstrated a cytoplasmic distribution for both isoforms. Interestingly, the expression ratio of OCT4B1/OCT4B transcripts and proteins was significantly elevated under the heat-stress condition.