1. CLOS, J., WESTWOOD, J.T., BECKER, P.B., WILSON, S., LAMBERT, K.
AND WU, C.
Molecular cloning and expression of a hexameric Drosophila heat shock
factor subject to negative regulation.
CELL 63 1085-1097 (1990).
2. RABINDRAN, S.K., GIORGI, G., CLOS, J. AND WU, C.
Molecular cloning and expression of a human heat shock factor, HSF1.
PROC.NATL.ACAD.SCI.U.S.A. 88 6906-6910 (1991).
3. SCHUETZ, T.J., GALLO, G.J., SHELDON, L., TEMPST, P. AND KINGSTON, R.E.
Isolation of a cDNA for HSF2: evidence for two heat shock factor genes
PROC.NATL.ACAD.SCI.U.S.A. 88 6911-6915 (1991).
Heat shock factor (HSF) is a transcriptional activator of heat shock genes
: it binds specifically to heat shock promotor elements, which are
palindromic sequences rich with repetitive purine and pyrimidine motifs .
Under normal conditions, HSF is a homotrimeric cytoplasmic protein, but
heat shock activation results in relocalisation to the nucleus .
Each HSF monomer contains 1 C-terminal and 3 N-terminal leucine zipper
repeats . Point mutations in these regions result in disruption of
cellular localisation, rendering the protein constitutively nuclear .
Two sequences flanking the N-terminal zippers fit the consensus of a bi-
partite nuclear localisation signal (NLS). Interaction between the N- and
C-terminal zippers may result in a structure that masks the NLS sequences
: following activation of HSF, these may then be unmasked, resulting in
relocalisation of the protein to the nucleus . The DNA-binding component
of HSF lies to the N-terminus of the first NLS region, and is referred to
as the HSF domain.
HSFDOMAIN is a 3-element fingerprint that provides a signature for the
heat shock factor domain. The fingerprint was derived from an initial
alignment of 5 sequences: the motifs were drawn from conserved regions
around the centre of the domain, motifs 2 and 3 spanning the well-conserved
region encoded by PROSITE pattern HSF_DOMAIN (PS00434). Two iterations on
OWL25.1 were required to reach convergence, at which point a true set
containing 21 sequences was identified.
An update on SPTR37_9f identified a true set of 35 sequences.