The crystal structure of the haematopoietic cell kinase Hck has been determined
at 2.6/2.9 A resolution. Inhibition of enzymatic activity is a consequence of
intramolecular interactions of the enzyme's Src-homology domains SH2 and SH3,
with concomitant displacement of elements of the catalytic domain. The
conformation of the active site has similarities with that of inactive
cyclin-dependent protein kinases.