Localization of TGN38 to the trans-Golgi network: involvement of a cytoplasmic tyrosine-containing sequence

Molecular dissection of the cytoplasmic tall of TGN38 identified an l 1-amino acid sequence sufficient to confer TGN localization. Within this sequence, the tetrapeptide YQRL was found to contain the most critical elements for this function. Although mutations of other residues within the 11-amino acid sequence elicited minor or no effects, the subtle increase in the number of cytoplasmic vesicles observed for some of the deletion mutants raises the possibility that residues NH2-terminal to YQRL may contribute to TGN localization. The requirements for specific residues at defined positions within this segment, however, would have to be much less stringent than for the YQRL motif.