Function
Two copies of IGLL1+VPREB1 (CD179B+CD179A) forms a pre-B cell receptor (pre-BCR) with the membrane-bound IgM (μ) heavy chain and the signaling molecules Igα and Igβ (CD79). Compared to the true BCR, IGLL1 and VPREB1 together take the place of the light chain, hence the name "surrogate light chain". In the surrogate light chain, IGLL1 takes the role of the C (constant) region while VPREB takes the role of the V ("variable") region.
The pre-BCR is found on the surface of proB and preB cells, where it is involved in transduction of signals for cellular proliferation, differentiation from the proB cell to the preB cell stage, allelic exclusion at the Ig heavy chain gene locus, and promotion of Ig light chain gene rearrangements.
IGLL1 is a mammalian-specific duplication of a immunoglobulin light chain lambda. It is a member of the immunoglobulin gene superfamily. This gene does not undergo rearrangement.