ABNORMAL EXPRESSION OF PROTEIN-4.1 IN SPERMATOZOA OF INFERTILE MEN WITH TERATOSPERMIA

Molecular defects responsible for morphologically abnormal spermatozoa (teratospermia) associated with male sterility are largely unknown. W e report defective expression of protein 4.1, a cytoskeletal protein i nitially recognised in red cells. In some patients with severely amorp hous sperm heads, protein 4.1 had an abnormal sub-cellular localisatio n (tail instead of head) and appeared as high-molecular-weight isoform s, especially a 135 kDa species instead of the 82 kDa isoform seen in fertile sperm. Because the 135 kDa isoform is characteristic of immatu re germ cells from testis, its presence in teratospermia suggests prof oundly disturbed sperm differentiation.