>1a21B (B:) observed residues (from ATOM records) tgraynltwkstnfktilewepksidhvytvqistrlenwkskcfltaetecdltdevvk dvgqtymarvlsypanttgfpeeppfrnspeftpyldtnlgqptiqsfeqvgtklnvtvq dartlvrrngtflslravfgkdlnytlyywrkktattntneflidvdkgenycfsvqavi psrkrkqrspesltect