Figure 1

Cloning of the novel human NUMB isoforms. (A) The nomenclature and structure of novel (NUMB5 and NUMB6) and previously reported NUMB isoforms. NUMB5 lacks the proline rich region PRR1 and NUMB6 lacks both the phosphotyrosine binding domain and PRR2 inserts and PRR1. (B) The amino acid sequence of NUMB isoforms. The PTB domain, PRR1, and PRR2 are shown in bold and the PTB domain (11 amino acids long) and PRR (48 amino acids long) inserts are underlined. (C) Western blot detection of novel NUMB isoforms. The two fractions of novel NUMB proteins differed from generic NUMB isoforms by approximately 10 kDa, most likely representing two novel isoforms of NUMB, NUMB5 and NUMB6. (D) Coomassie blue stained protein bands used for mass spectrometry protein sequencing. Protein bands indicated by red arrows correspond to NUMB5 and NUMB6, respectively. β-actin fraction served as an internal control in mass spectral sequence analysis.