May 8th, 2011


 Three-dimensional structures of several transport
intermediates of SERCA1a, stabilized by structural analogues
of ATP and phosphoryl groups, are now available at atomic
resolution. This has enabled the transport cycle of the protein to
be described, including the coupling of Ca2+ occlusion and
phosphorylation by ATP, and of proton counter-transport and
dephosphorylation. From these structures, Ca2+-ATPase
gradually emerges as a molecular mechanical device in which
some of the transmembrane segments perform Ca2+ transport
by piston-like movements and by the transmission of
reciprocating movements that affect the chemical reactivity of
the cytosolic globular domains.