A Murine fer Testis-Specific Transcript (ferT) Encodes a Truncated Fer Protein

A cDNA for a potential tyrosine kinase-encoding mRNA was isolated from a mouse testis cDNA library. In a survey of eight mouse tissues, a transcript of 2.4 kilobases restricted to testis tissue was found. The mRNA encodes a 453-amino-acid protein of 51,383 daltons, the smallest tyrosine kinase protein ever described. RNA synthesized from the cDNA template directs the synthesis of a 51,000-Mr protein in a cell-free translation system. The carboxy-terminal 409 amino acids are 98 and 90% identical to the carboxy halves of the rat and human Fer proteins, respectively. This suggests that the cDNA represents an alternatively spliced testis-specific fer mRNA and is therefore termed by us ferT. On the basis of the appearance time of the fer mRNA in the testis of maturing neonatal mice, we speculate on the role played by this protein in the development of this organ.