Unique amino acid sequences of Bence Jones proteins in the urine of patients with adult Fanconi syndrome.

The amino-terminal amino acid sequences of Bence Jones (BJ) proteins isolated from the urine specimens of two patients (JBL and PSM) with adult Fanconi syndrome were determined. Both BJ proteins JBL and PSM are of the VkI subclass. However, protein JBL contains tyrosine at position 14 whereas protein PSM contains glutamine at position 40. Neither tyrosine 14 nor glutamine 40 has previously been reported for immunoglobulin (Ig) L-chains of any species including humans, the mouse, rabbit, rat, guinea pig. pig, dog, chicken, turkey, and shark. In addition, protein JBL contains alanine 22 whereas protein PSM contains arginine 30. Both alanine 22 and arginine 30 have been only rarely found in Ig L-chains.