Plant Biology. In the article “Differential expression of two isopentenyl pyrophosphate isomerases and enhanced carotenoid accumulation in a unicellular chlorophyte” by Zairen Sun, Francis X. Cunningham, Jr., and Elisabeth Gantt, which appeared in number 19, September 15, 1998, of Proc. Natl. Acad. Sci. USA (95, 11482–11488), the following correction should be noted. In Fig. 3 the lightly shaded sequences, representing amino acid identity of four of five sequences, was inadvertently lost in the electronic submission process.

Figure 3.

Amino acid sequence alignment of IPP isomerases predicted by cDNAs of Haematococcus pluvialis (IPIHp1 and IPIHp2) and Chlamydomonas reinhardtii (IPICr1) are compared with sequences from the flowering plants Clarkia brewerii (IPICb2) (29) and Arabidopsis thaliana (IPIAt1) (30). The sequences were aligned using the program clustalw (http://dot.imgen.bcm.tmc.edu:9331/multialign) and shaded using genedoc (http://www.concentric.net/∼Ketchup/gddl.htm). The dark shading with white letters indicates amino acid identity for the aligned residue for all five proteins whereas the lightly shaded sequences represent amino acid identity for four of five sequences. The lines above the sequences indicate differences in the predicted amino acid sequences of IPIHp1 and IPIHp2. The inverted arrowhead (▾) above IPIHp1 designates the location of a truncation from the N terminus. Residues required for catalytic activity (31) are marked by upright arrowheads (▴).