S-100 are small dimeric acidic calcium and zinc-binding proteins [1] abundant
in the brain. They have two different types of calcium-binding sites: a low
affinity one with a special structure and a 'normal' EF-hand type high
affinity site. The vitamin-D dependent intestinal calcium-binding proteins
(ICaBP or calbindin 9 Kd) also belong to this family of proteins, but it does
not form dimers. In the past years the sequences of many new members of this
family have been determined (for reviews see [2,3,4]); in most cases the
function of these proteins is not yet known, although it is becoming clear
that they are involved in cell growth and differentiation, cell cycle
regulation and metabolic control. These proteins are:
Calcyclin (Prolactin receptor associated protein (PRA); clatropin; 2a9;
5B10; S100A6).
Calpactin I light chain (p10; p11; 42c; S100A10).
Calgranulin A (cystic fibrosis antigen (CFAg); MIF related protein 8 (MRP-
8); p8; S100A8).
Calgranulin B (MIF related protein 14 (MRP-14); p14; S100A9).
Trichohyalin [7]. This is a large intermediate filament-associated protein
that associates with keratin intermediate filaments (KIF); it contains a S-
100 type domain in its N-terminal extremity.
A number of these proteins are known to bind calcium while others are not (p10
for example). Our EF-hand detecting pattern (see <PDOC00018>) will fail to
pick those proteins which have lost their calcium-binding properties. We
developed a pattern which unambiguously picks up proteins belonging to this
family. This pattern spans the region of the EF-hand high affinity site but
makes no assumptions on the calcium-binding properties of this site.
Lee S.-C. Kim I.-G. Marekov L.N. O'Keefe E.J. Parry D.A.D. Steinert P.M.
Title
The structure of human trichohyalin. Potential multiple roles as a functional EF-hand-like calcium-binding protein, a cornified cell envelope precursor, and an intermediate filament-associated (cross-linking) protein.
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