Fig. 4. Cytoplasmic tail sequences of Limp II, Lamp 1, LAP and mutants derived from LAP or Lamp 1. The amino-acid sequences are shown using the one-letter code, with the C-terminus to the right. Signals known to be important for intracellular sorting are printed in bold. The colour of the bars corresponds to those used in Fig. 1 to indicate LAP (grey bars) or Lamp 1 (open bars) sequences. In LAP7, the C-terminal seven residues were removed by introducing a premature stop codon at the position of alanine 13. The following mutant proteins all contain the lumenal and the transmembrane part of LAP as a reporter. Their names indicate the type and origin of their tyrosine-sorting motif they contain: LAP7/YQTI is a mutant form of the LAP7 tail in which the LAP tyrosine motif was substituted for that of Lamp 1. In Lamp 1/YRHV, the tyrosine motif within the Lamp 1 tail sequence is substituted for that of LAP. LAP7/TI and Lamp 1/HV represent cytoplasmic tail mutations in which the last two residues of the tyrosine motifs of LAP7 and Lamp 1 were exchanged.