Immunogen sequence: PSFTTDSCLD QEVKDALLCD AMTLVNLRGC DKRKVMEEDK RRVKERLFQC YRQPRESRCA RCLACV. Polyglutamylase which preferentially modifies alpha-tubulin. Involved in the side-chain elongation step of the polyglutamylation reaction rather than in the ini