Gene Networks Database
purpuratus Genes in Development: Transcription Factors
SpP3A2 codes for transcription factor.
It is a negative spatial regulator of CyIIIa expression.
SpP3A2 factor represses the expression of CyIIIa gene in oral ectoderm
by binding to two P3A sites in the proximal module (Zeller et al., 1995).
The SpP3A2 protein has no significant similarity to any
previosly reported protein sequence.
The sequences essential for the DNA-binding activity
of SpP3A2 span a broad region, the N-terminus of which
occurs between amino acid positions 25-90, and the
C-terminal boundary between residues 222-358,
i.e. a DNA-binding domain of SpP3A2 includes at least
130 amino acids.
SpP3A2 DNA binding domain shows no similarity to
any previously characterized DNA-binding motif. SpP3A2 is thus
a novel, sequence specific recognition factor.
Two regions of SpP3A2 are relatively rich in serine and theonine
and may include sites of phosphorilation detected in the
affinity-purified protein (Calsone et al., unpublished
Near the N terminus, the sequence spanning residues 4 to
28 is 36% serine plus theonine (S+T); residues 266-290 are
28% (S+T) and residues 364-389 are 26,9% (S+T).
The remaining sequences in SpP3A2 are average 11,7% (S+T).
This protein also has a very glutamine-rich region, similar to
those detected in Oct-1 and Zeste. Thus, the SpP3A2 sequence
between residues 308 and 336 is 37,9% glutamine, compared
to 6,7% glutamine in the premainder of the protein (Hoog et al., 1991).
Most likely, SpP3A2 factor binds DNA as a dimer (Zeller et al., 1995).
Egg cytoplasm and pronuclus, embryonic nuclei (Zeller et al., 1995).
Maternal SpP3A2 mRNA is present in unfertilized egg.
It is very low-abundance factor.
There are about 1100 copies of the SpP3A2 mRNA per egg (Hoog et al., 1991).
At its peak in mid-late cleavage the average blastomere
nucleus contains about 3000 molecules of SpP3A2, but
there are only about 1200 molecules/nucleus at blastula stage. This level remains
approximately constant at least through the late gastrula period.
(Calzone et al., 1991).
The average SpP3A2 protein level (molecules/nucleus)
Method: Immunological blot reaction
Reference: Zeller et al., 1995
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