hide
Free keywords:
-
Abstract:
The Src-homology 3 (SH3) region is a protein domain consisting of
approximately 60 residues. It occurs in a large number of eukaryotic
proteins involved in signal transduction, cell polarization and
membrane-cytoskeleton interactions. The function is unknown, but it is
probably involved in specific protein-protein interactions. Here we
report the crystal structure of the SH3 domain of Fyn (a Src family
tyrosine kinase) at 1.9 angstrom resolution. The crystals have two SH3
molecules per asymmetric unit. These two Fyn SH3 domains are not related
by a local twofold axis. The crystal structures of spectrin and Fvn SH3
domains as well as the solution structure of the Src SH3 domain show
that these all. have the same basic fold. A protein domain which has the
same topology as SH3 is present in the prokaryotic regulatory enzyme
BirA. The comparison between the crystal structures of Fyn and spectrin
SH3 domains shows that a conserved surface patch, consisting mainly of
aromatic residues, is flanked by two hairpin-like loops (residues 94-104
and 114-118 in Fyn). These loops are different in tyrosine kinase and
spectrin SH3 domains. They could modulate the binding properties of the
aromatic surface.
