Gene Networks Database
purpuratus Genes in Development: Transcription
SpZ2-1 (formerly SpP3A1) factor (Roger Anderson et al.,1994) codes for a Zn-finger DNA-binding protein.
It binds in vitro specifically to the P3A target site
in the skeletogenic SM50 gene and to the the similar
target sequence in the CyIIIa gene.
It also binds in vitro to the closely spaced P3A sites in the
The function of this gene is unclear (Hoog et al., 1991).
The open reading frame of the SpZ2-1 sequence specifies
a protein with a molecular mass of 42*10^3 (387 amino acids).
This protein has a high content of serine, theonine
and proline, together about 29%.
The amino acid terminal region of the SpZ2-1 protein
(positions 1-53) is strongly acidic and can function as a transcriptional
activator region. A short strongly basic
region (7/11 amino acids) appears after position 237.
The SpZ2-1 protein has no significant similarities with
the other known DNA-binding proteins except for two
regions which conform to the general form of Zn-finger motifs:
Phe-X-Cys-X(2-4)-Cys-X3-Phe-X5-Leu-X2-His-X(3-5)-His [as described
by Miller et al.(1985) and Berg (1988)].
Egg cytoplasm and pronuclus, embryonic nuclei (Zeller et al., 1995).
SpZ2-1 factor is present in unfertilyzed
eggs, and enters the embryonic nuclei early in development.
There are about 300 copies of SpZ2-1 mRNA per egg.
At 4h postfertilization there are approximately 600 copies
of the SpZ2-1 mRNA per embryo of average length about
At 24h there are about 2000 copies of SpZ2-1 mRNA
per embryo (at that stage - about 4 molecules per/cell).
After that the level of transcripts begins to fall until
the early gastrula, when they are not detected (Hoog et al., 1991).
The average SpZ2-1 protein levels (molecules/nucleus)
Method: Immunological blot reaction
Reference: Zeller et al., 1995
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