the gene for protein l contains five components: a signal sequence of 18 amino acids; a nh2-terminal region ("a") of 79 residues; five homologous "b" repeats of 72-76 amino acids each; a cooh terminus region of two additional "c" repeats (52 amino acids each); a hydrophilic, proline-rich putative cell wall-spanning region ("w") after the c repeats; a hydrophobic membrane anchor ("m"). the b repeats (36kd) were found to be responsible for the interaction with ig light chains.