Fibrous Sheath Interacting Protein 2 (FSIP2)

The 357 bp Fsip2 cDNA was used as a probe to screen a mouse testis cDNA library and sequencing of overlapping clones added 1638 bp to the Fsip2 sequence. An open reading frame was present throughout the entire 1995 bp sequence. Northern analysis with total RNA from 11 mouse tissues and from mixed germ cells was used to determine the tissue distribution and size of the Fsip1 and Fsip2 transcripts. Transcripts 1.6 and 2 kb in length for Fsip1 and approximately 20 kb in length for Fsip2 were detected only in testis and mixed germ cells. However, Fsip2 transcripts were first observed on Day 16, corresponding to the latter part of the meiotic phase of spermatogenesis. FSIP2 bound to construct aa 202–247, containing a region near the N-terminal end of the processed protein and encompassing PKA-binding domain A, but did not bind to constructs aa 237–849 or aa 125–218 of AKAP4.