Work in the laboratory on the function of crystallins in the lens has also focused on the b-crystallin gene family.  There are 6 transcriptionally active b-crystallin genes encoding 7 polypeptides in both birds and mammals.  These proteins associate in the lens to form two types of high molecular weight macromolecules, b low  (40 to 80 kd, dimers to tetramers) and b high (160 to 200 kd, octomers).  These proteins appear to be critical for lens transparency since b-crystallin mutations and/or proteolysis can cause cataracts.  Each b-crystallin gene is independently regulated and it appears that cells born at different developmental times have very different b-crystallin profiles.  After b-crystallins are translated, many of the subunits undergo a maturation process which can involve proteolytic processing, phosphorylation, glycosylation and deamidation.  Studies on the function of these proteins in the lens can help us understand the molecular interactions responsible for normal lens transparency and how alterations in these interactions can lead to cataract.