Cloning, sequencing and expression of stem cell factor (c-kit ligand) cDNA of brushtail possum (Trichosurus...

By means of reverse transcription polymerase chain reaction (RT-PCR), three stem cell factor (SCF) cDNAs (822-738 bp in size) were amplified from brushtail possum ovarian poly (A)+ RNA. The largest and smallest of these cDNAs were cloned and sequenced. Characterization of these cDNAs has revealed that possum SCF has approximately 75% and 66% homology to SCF of eutherian mammals at the nucleotide level and the predicted amino acid level respectively. Nucleotide sequencing shows that the 738-bp cDNA represents an mRNA splice variant, equivalent to that found in eutherian mammals, in which an exon (84 bp) encoding a potential proteolytic cleavage site is removed. Comparison of the predicted possum SCF amino acid sequence with the predicted SCF amino acid sequences from eutherian mammals reveals conservation of all cysteine residues and 3 of 4 potential N-linked glycosylation sites. In addition, the hydropathicity profile of the possum SCF protein is similar to that of eutherian SCF suggesting that protein conformation is conserved. Northern analysis was used to characterize possum SCF gene expression in adult ovary and testis. A major transcript of 9 kb was observed in both ovarian and testicular tissue. The conservation of the SCF gene and its predicted protein, suggests that SCF in the possum has similar biological activities to SCF in eutherian mammals.