Figure 1.

Immunostaining of Endogenous PCYT1A in Selected Mouse Tissues

(A) Simplified schematic of the two major PC biosynthetic pathways in eukaryotes. The CDP-choline (Kennedy) pathway is shown in red and the methylation pathway in blue. Key enzymes discussed in the text are shown in upper case (mammals) or lower case (yeast). Pct1/CCTα/PCYT1A, choline-phosphate cytidylyltransferase A; P-Cho, phosphocholine; CDP-Cho, cytidine diphosphate-choline; CDP-Etn, cytidine diphosphate-ethanolamine; PA, phosphatidic acid; DAG, diacylglycerol; TAG, triacylglycerol; PC, phosphatidylcholine; PE, phosphatidylethanolamine; PS, phosphatidylserine; Cho, choline.

(B) (i) Immunostaining of adult mouse retina indicates that PCYT1A localizes to the nuclear membrane in the outer nuclear layer. SC, sclera; CH, choroid; RPE, retinal pigmented epithelium; OS, outer segments of rods and cones; ONL, outer nuclear layer; OPL, outer plexiform layer; INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer. (ii) Zoomed-in images of the indicated field in (i).

(C) (i) In the femoral growth plate of 15-day-old mice, PCYT1A localizes to the nuclear membrane of chondrocytes in the hypertrophic (HZ) but not in the resting (RZ) or proliferative (PZ) zone of growth plates. (ii) Zoomed in images of the indicated field in (i).

(D) In ad-libitum chow-fed adult mice, PCYT1A localizes to the nuclear membrane in wild-type (WT) but not in Mtp knockout hepatocytes, which have impaired lipoprotein synthesis.

(E) (i) PCYT1A localizes to the intranuclear region of adult mouse inguinal white adipocytes but translocates to the nuclear membrane upon adipogenic induction in OP9 cells (ii). Lipid droplets (LDs) were stained with BODIPY (green) as described in the STAR Methods. D0–D3 indicate day after onset of differentiation.

Scale bars, 20 μm. See Figure S1.