The scavenger receptor cysteine-rich (SRCR) superfamily, which include
s proteins expressed by leukocytes, can be subdivided into groups A an
d B. Group B contains the lymphocyte cell-surface receptor CD6. This a
rticle reviews recent progress in understanding the interaction betwee
n CD6 and its ligand, activated leukocyte cell adhesion molecule (ALCA
M). Analysis of the CD6-ALCAM interaction may help to understand how o
ther SRCR domains bind to their ligands.