Program of Biochemistry and Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm & Carlton Streets, Buffalo, New York, NY 14263, USA

Correspondence to: M F Kulesz-Martin, Program of Biochemistry and Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm & Carlton Streets, Buffalo, New York, NY 14263, USA

^aCurrent address: Department of Dermatology L468, Oregon Health Sciences University, School of Medicine, 3181 SW Sam Jackson Park Road, Portland, Oregon, OR 97201-3098, USA

A novel spermatogenesis associated factor (SPAF) was found to be aberrantly expressed at the malignant conversion stage in a clonal epidermal model of chemical carcinogenesis. Sequence analysis revealed two ATPase modules, classifying this gene as a new member of the AAA-protein family (ATPase associated with diverse activities). Immunohistochemical staining of mouse testis sections with SPAF antibody localized expression to spermatogonia and early spermatocytes in the basal compartment of the seminiferous tubules. Northern and Western analysis of SPAF expression in testes of mice at different developmental stages confirmed its expression at early stages of spermatogenesis. In view of a mitochondrial-localization-like signal, sequence similarities to membrane-associated proteins, ATP binding properties, and intracellular expression patterns in testis, we speculate that SPAF protein may be involved in morphological and functional mitochondrial transformations during spermatogenesis. Ectopic expression of the SPAF gene in malignant epidermal cells may signify adoption of an early germ cell-like phenotype advantageous in malignant conversion. Oncogene (2000) 19, 1579-1588.

SPAF; AAA-protein; spermatogenesis; carcinogenesis; mitochondria