|Detection of Mouse and Rat PU.1/Spi‑1 by Western Blot. Western blot shows lysates of NR8383 rat alveolar macrophage cell line and J774A.1 mouse reticulum cell sarcoma macrophage cell line. PVDF membrane was probed with 0.1 µg/mL of Rat Anti-Mouse PU.1/Spi‑1 Monoclonal Antibody (Catalog # MAB7124) followed by HRP-conjugated Anti-Rat IgG Secondary Antibody (Catalog # HAF005). A specific band was detected for PU.1/Spi‑1 at approximately 40 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 1.|
|PU.1/Spi‑1 in J774A.1 Mouse Cell Line. PU.1/Spi‑1 was detected in immersion fixed J774A.1 mouse reticulum cell sarcoma macrophage cell line using Rat Anti-Mouse PU.1/Spi‑1 Monoclonal Antibody (Catalog # MAB7124) at 10 µg/mL for 3 hours at room temperature. Cells were stained using the NorthernLights™ 557-conjugated Anti-Rat IgG Secondary Antibody (red, upper panel; Catalog # NL013) and counterstained with DAPI (blue, lower panel). Specific staining was localized to nuclei. View our protocol for Fluorescent ICC Staining of Non-adherent Cells.|
Spi-1 (SFFV proviral integration 1 protein; also PU.1 and Sfpi1) is a 37-41 kDa member of the ets family of transcription factors. It is both an RNA and DNA binding protein that is found in hematopoietic cells such as B cells, neutrophils, macrophages and dendritic cells (DC). Spi-1 can act as both a transcriptional activator and repressor. In DC, Spi-1 promotes the expression of CD80, CD86 and CD11b, while in proerythroblasts it blocks GATA-1 induced transcriptional activation. Spi-1 binds to DNA as a monomer and interacts with multiple factors such as Runx-1, IRF8, GATA-1 and c-Jun. Mouse Spi-1 is 272 amino acids (aa) in length. It contains a transactivation region (aa 7-117), a PEST domain (aa 118-164), and a DNA-binding domain (aa 165-266). Phosphorylation on Ser41, 142 and 148 increases activity. There is one alternative start site at Met7. Over aa 1-169, mouse Spi-1 shares 88% and 81% aa identity with rat and human Spi-1, respectively.