Schematic diagram of constructs.

F1mpl and F1flt3r constructs encode fusion proteins containing 14 amino acids from the amino terminus of c-Src (to allow for myristylation and membrane association), FKBP12 (to allow for binding to the CID FK1012), the intracellular portion of either murine mpl or murine Flt-3, respectively, and a hemagglutinin (HA) epitope tag (to permit detection using the monoclonal antibody HA.11). The construct F36Vmpl is identical to F1mpl except for a phenylalanine to valine substitution at the 36th amino acid of the FKBP12 domain, which allows for binding to the CID AP20187. The F36Vgcsfr construct contains the intracellular portion of the murine GCSF receptor but is otherwise identical to F36Vmpl. The membrane distal F36V domain is “codon wobbled” to reduce repetitive sequences, preventing recombination.