Mutations of amino acids at positions 10 and 29 affect p12^I cleavage and cellular localizations. (A) Single-letter amino acid code of p12^I from HTLV-1. The arrows indicate the computer-predicted cleavage sites. (B) Schematic representation of the p12^I mutants. Changes in amino acid positions are indicated on the top. L9 and S10 were changed to alanines. Glycine 29 was changed to serine. The Δ symbol signifies deletion of amino acids at the amino terminus for the truncated mutants Δ24 and Δ29. (C) Cell lysates from the 293T cells transfected with the wild-type p12^I or the p12^I mutants were analyzed by Western blot with anti-HA antibody. (D) Localization of p12^I, p12^IG29S, and p12^IΔ29 in Jurkat T cells stained with anti-HA antibody. (E) HeLa cells expressing p12^I and p12^IG29S were costained with an anti-PDI antibody. (F,G) Localization of p12^I, p12^IG29S, and p12^IΔ29 in HeLa cells compared with ER and Golgi markers. Red-ER is used as the ER marker, whereas an antibody to mannosidase II (Mann II) is used to label the Golgi apparatus.