Аннотация:Recoverin, initially named “p26,” is a Ca2+-
binding protein with a predominantly retinal
localization, which belongs to the neuronal calcium
sensor (NCS) protein family. The recoverin
molecule consists of 201 amino acid residues and
contains four potential EF-hand Ca2+-binding
sites, of which only two – EF-hands 2 and 3 –
are capable of binding calcium. The N-terminus of
recoverin is acylated, mainly myristoylated. Due
to the mechanism of Ca2+-myristoyl switch, compartmentalization
of recoverin is changed from a
soluble Ca2+-free form to a membrane-bound Ca2
+-containing form, and vice versa, depending on
an external calcium concentration. In the Ca2+-
free form, the N-terminal myristoyl moiety of
recoverin is buried into the hydrophobic pocket
of the protein; on calcium binding, the
myristoylated N-terminus is exposed, providing
membrane association of recoverin. Recoverin is
suggested to operate as a Ca2+-sensor of rhodopsin
kinase (G-protein-coupled receptor kinase
1, GRK-1), which catalyzes phosphorylation and
thus desensitization of the visual receptor rhodopsin.
In cancer, recoverin can also be a
paraneoplastic (or onconeural) antigen, the aberrant
expression of which in malignant tumors of
some patients causes an autoimmune response
and the development of paraneoplastic retina
degeneration or cancer-associated retinopathy.
An important feature of the CAR syndrome and
underlying autoantibodies against recoverin is
that they can be detected long before the clinical
diagnosis of the corresponding tumor. Such a
feature of the autoantibodies could be useful to
clinicians to predict the future development of a
particular cancer.