Subject: Novel kinase: Haspin
We have identified a Drosophila Haspin kinase by analysis of genomic and
EST sequence. A HMM search of the genome for kinase domains was followed by
gene extension using EST sequences and genewise. The protein sequence
(TrEMBL: P83103) is complete with UTRs at both ends. It encodes a divergent
protein kinase domain that bears strong similarity to the Haspin gene of
mouse and human and has likely orthologs in S. pombe, C. elegans (three or
more genes), Arabidopsis, S. cerevisiae and a number of other vertebrates.
All these genes have a conserved C-terminal kinase domain and a divergent N
terminus.
Mouse Haspin is selectively expressed in testicular germ cells and has
shown biochemical kinase activity (Tanaka et al, JBC (1999)  274:17049-57 ).
Overexpressed mouse haspin localises to the nucleus where it can bind DNA
and block cells in G1 phase, in wild type or mutant form where the kinase
ATP-binding region has been deleted. The fly gene has a predicted nuclear
localisation, by the PSORT II prediction, but does not contain the weak
leucine zipper found in the mouse gene, and so might not directly bind DNA.
19 ESTs are known from this gene, from 17 clones derived from embryo (14
LD library clones and 4 RE library clones) and ovary (1 GM ovary library
clone), so expression appears to be much higher in embryo than larva or
adult. The map location of this gene is still unclear; the sequence is
derived from two different genomic contigs (|gb|AE003029 and gb|AC005334).
The first is unmapped, and the second contains the spen gene which maps to
21B2-4, but this may be a chimeric contig.
\-Gerard Manning.