Approximately two decades have passed since the description of the first gene in
the Candida albicans ALS (agglutinin-like sequence) family. Since that time, much has
been learned about the composition of the family and the function of its encoded cellsurface
glycoproteins. Solution of the structure of the Als adhesive domain provides
the opportunity to evaluate the molecular basis for protein function. This review article
is formatted as a series of fundamental questions and explores the diversity of the Als
proteins, as well as their role in ligand binding, aggregative effects, and attachment to
abiotic surfaces. Interaction of Als proteins with each other, their functional equivalence,
and the effects of protein abundance on phenotypic conclusions are also examined.
Structural features of Als proteins that may facilitate invasive function are considered.
Conclusions that are firmly supported by the literature are presented while highlighting
areas that require additional investigation to reveal basic features of the Als proteins,
their relatedness to each other, and their roles in C. albicans biology.