Identification of a third type of lambda light chain in mouse immunoglobulins.

Abstract
A 3rd type of mouse .lambda. chain was identified in the course of examining L chains from 4 myeloma proteins and 2 monoclonal antibodies. Based on their antigenic properties and a characteristic COOH-terminal tryptic peptide, the L chains from these Ig were previously provisionally identified as .lambda.2 chains. Four of these chains, designated now as .lambda.3 (or .lambda.III), shared constant region features that clearly distinguished them from the other types of mouse .lambda. chains (.lambda.1 and .lambda.2). The amino acid sequence of more than 90% of the .lambda.3 constant region (from position 120 to the COOH-terminus) was determined. In this region the .lambda.3 sequence differs from the .lambda.2 constant region at 5 positions and from the .lambda.1 constant region at about 30 positions.