Fig 6.

Identification and phosphorylation of two alternative HIP1 isoforms. (A) Diagram of alternative human HIP1 transcripts and their amino acid sequences, designated hHIP1a and hHIP1b. These isoforms differ only in their initial exon, resulting in alternative N-terminal amino acid sequences. (B to E) HEK293T cells were cotransfected with various RTKs and either HIP1a or HIP1b, both of which were tagged with Myc. Immunoprecipitation was performed with anti-Myc beads, and HIP1 phosphorylation was detected with antiphosphotyrosine antibody 4G10. (B) EGFR phosphorylates HIP1b less than HIP1a in the presence or absence of NaVa. (C) EGFRvIII phosphorylates HIP1b to a slightly lesser degree than that for HIP1a in both the presence and absence of NaVa. (D) PDGFβR phosphorylates both HIP1b and HIP1a. (E) H/P and T/P phosphorylate HIP1a and HIP1b equally in both the presence and absence of NaVa.