Fig. 1. NgCAM contains a sufficient somatodendritic sorting signal in its cytoplasmic tail. (A,B) Cultured hippocampal neurons were transfected with DsRed (red) and either the LDLR-based chimera LexNct1-42 (A) or LexNct1-42(Y33A) (B). The cell-surface population of the chimeras was stained with an antibody against an extracellular epitope of LDLR (anti-Lex; green). In A,B, the top row shows the soma region containing the dendrites (arrowheads), whereas the bottom row shows the distant distal portions of the axons (arrows). (C-E) The extent of surface polarity for the three constructs LCT, LexNct1-42 and LexNct1-42(Y33A) (shown diagrammatically in C) was determined by measuring the average fluorescence intensity along distal axons and dendrites. The axon/dendrite polarity index (PI) is the ratio of axon/dendrite intensities. The polarity index was determined for 20-25 cells and the percentage of cells displaying preferential axonal accumulation (PI>2), preferential somatodendritic accumulation (PI<0.5) or uniform distribution is plotted in D. The average PI for 20-25 cells from three independent experiments is shown in E. ^**P<0.001, ^*P<0.01, Student's t-test.