Table 4.

Proposed roles of single conserved residues in vertebrate PTP domains that reside outside the 10 PTP motifsa

Amino acid in PTP1BConserved by amino acid identityProposed roles of the residues
Ile19E (>80%)Definition of α2′ helix structure
Glu115 E (100%)Conserved H bonds with Arg221
Arg156R (>80%)Definition of β10-sheet
Arg169R (>80%)Definition of β11-sheet
Leu192L (>80%)Definition of the α3-helix structure
Arg254 R (>90%)H bonds with PTP loop
Arg257 R (100%)H bonds with PTP loop lowering pKa of Cys215
  • a Conserved residues were identified from our multiple-sequence alignment of 113 vertebrate PTP domains. Underscored bold letters represent invariant residues. Residues in bold letters are conserved in ≥90% of the sequences, and non-bold letters represent ≥80% conservation.