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Objective: To examine the expression profiles of the proteins translated from Acpin1 mRNA in germ cells. Methods: Northern and western blotting of various tissues and immunohistochemical analysis of germ cells were carried out in a mouse model. Results: ACPIN1 protein was transcribed from the longer, 3′ open reading frame (ORF) of Acpin1. An alternative-splicing variant, Acpin1vs, contained only the smaller, 5′ ORF of the full-length Acpin1 gene. Its gene product, SAGSIN1, was expressed specifically in salivary glands. Retrotransposed regions of Acpin1 homology were also detected in various chromosomes, and intronless paralogous genes on the X chromosome were expressed in the testis and other tissues. The genomic structure of Acpin1 is highly conserved in mammals. Conclusion: The two ORFs on the Acpin1 mRNA are independently translated in differentiated cells. Analysis of gene Acpin1 might clarify the molecular mechanism of spermatogenesis. [ABSTRACT FROM AUTHOR]

Development of spermatozoa is a complex process involving specific morphological formation of flagella, nucleus and mitochondria. Although detailed morphological observations of these events are available, the molecular mechanisms remain to be fully elucidated. We report here the molecular cloning and characterization of mouse spergen-1 encoding a sperm specific mitochondrial protein, from a haploid germ cell-specific subtracted cDNA library of mouse testis. Isolated cDNA is c. 0.7 kb and contains a 465 bp ORF that encodes mouse spergen-1, a sperm mitochondrial protein consisting of 154 predicted amino acids. Antibodies raised against mouse Spergen-1 identified a testisspecific c. 18 Mr × 10³ band in Western blot analysis. The protein was localized to the mitochondria of mouse sperm. Comparison of the mouse and human genomic sequences showed that 55 bps of the 5'-upstream region containing a CAAT box and binding sequence for NF-κB is conserved and could be important for specific expression of mouse spergen-1 in haploid germ cells. [ABSTRACT FROM AUTHOR]