FIG. 1.

Schematic representation of chimeric receptor cDNAs used to examine virus receptor function. Numbered boxes represent regions encoding the five predicted extracellular domains (left to right, 5′ to 3′). The regions derived from Pit1 are shown in black; those derived from Pit2 are shown in white. Chimeric receptors are named by using single letters to designate the source for each of the five extracellular domains (A for Pit2, G for Pit1). Restriction enzyme sites are given in their appropriate locations in the receptor cDNAs; nucleotide positions of the restriction sites are given in the Materials and Methods section. The NheI and BglII sites are given in parentheses because they were originally introduced as silent mutations in either Pit1 or Pit2 (8).