FIG. 8.

Schematic representations of Pit1 receptor protein based on Kyte-Doolittle (12) or PHD PredictProtein (23) systems. Cylinders, TM domains; lines above and below, extracellular and cytoplasmic domains, respectively. The residue numbers that represent the boundaries of the TM domains are shown at the opposing ends of each cylinder. Asterisk, potential N-glycosylation site at position 96. TM4 of Pit1 (residues 129 to 146) is present in the PHD-predicted model but absent from the Kyte-Doolittle system-based model. TM7 (residues 512 to 532; green cylinder) becomes part of the large cytoplasmic loop (green line) in the PHD model. Yellow lines, relative locations of region A; red line and cylinder (TM7 and flanking residues of PHD model), region B (residues 232 to 260).