Fig. 1: RNA and protein expression patterns of 181-Rik.

A Relative RNA expression levels of 181-Rik in various murine tissues were determined by qRT-PCR assay. Data were presented as mean ± SD (n = 3). B Adult mouse retinal section in situ hybridized with a 181-Rik probe. Scale bar: 50 μm. C, D scRNA-seq analysis of adult mouse retinal cells indicates a widespread expression of 181-Rik in nearly all retinal cell classes. E, F1–H1, F2–H2, F3–H3 Fluorescent RNAscope assay of 181-Rik on adult mouse retinal sections (E) and in combination with immunolabeling with antibodies against Iba1, Tfap2a, and Rbpms (F1–H1, F2–H2, F3–H3), which are markers for microglia, amacrine cells, and ganglion cells, respectively. All sections were also counterstained with nuclear DAPI (blue). Scale bar: 15 μm. I Alignment of putative Stmp1 amino acid (AA) sequences from the indicated species. Numbers indicate AA length. J Schematic of tagged Stmp1 (Stmp1-Flag) and control (Control-Flag) expression constructs driven by the CMV promoter. The putative 181-Rik ORF containing the ATG start codon is fused with a Flag tag sequence. K Western blotting analysis of total proteins from HEK293T cells transfected with the Control-Flag or Stmp1-Flag construct. Both the Flag antibody and a non-commercial Stmp1 antibody detected the expression of the exogenous Stmp1-Flag protein. β-actin served as the internal protein control. L Western blotting analysis of proteins from the whole cell, cytoplasm, mitochondria, and nucleus of HEK293T cells transfected with the Stmp1-Flag construct using the indicated antibodies. M1–P1, M2–P2, M3–P3, Q–T Immunostaining of HEK293T cells transfected with the Control-Flag or Stmp1-Flag construct with anti-Flag and anti-Tomm20 or MitoTracker. Flag and Tomm20 or MitoTracker were co-immunolabeled in mitochondria. Scale bars: 20 μm. U–W Double-immunostaining of untransfected HEK293T cells with a commercial Stmp1 antibody and an anti-COX4 antibody, along with counterlabeling by nuclear DAPI (blue). STMP1 was colocalized with COX4 in mitochondria. Scale bar: 25 μm. GCL ganglion cell layer, INL inner nuclear layer, IPL inner plexiform layer, ONL outer nuclear layer, OPL outer plexiform layer.