Novel actin-like proteins T-ACTIN 1 and T-ACTIN 2 are differentially expressed in the cytoplasm and nucleus of mouse haploid germ cells

Biol Reprod. 2003 Aug;69(2):475-82. doi: 10.1095/biolreprod.103.015867. Epub 2003 Apr 2.


We isolated cDNA clones for the novel actin-like proteins T-ACTIN 1 and T-ACTIN 2, which are expressed specifically in the mouse testis. These clones were from a subtracted cDNA library that was enriched for haploid germ cell-specific cDNAs. The mRNA sizes and deduced molecular masses of t-actin 1/mACTl7b and t-actin 2/mACTl7a were 2.2 kilobases (kb) and 1.8 kb, and Mr 43.1 x 10(3) and Mr 47.2 x 10(3), respectively. The two deduced amino acid sequences had 60% homology, and they had approximately 40% homology with other actins. The T-ACTINs contained some of the conserved regions seen in other actins. Although the cellular locations of these two proteins are quite different (T-ACTIN-1 was found in the cytoplasm and T-ACTIN-2 was located in the nucleus), the expression of their proteins and mRNAs is controlled during development and limited during spermiogenesis. In contrast, only T-ACTIN-2 was present in sperm heads and tails. These results suggest that T-ACTINs play important roles in sperm function and in the specific morphogenesis of spermatozoa during spermiogenesis.

MeSH terms

  • Actins / biosynthesis*
  • Actins / genetics*
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Blotting, Northern
  • Blotting, Western
  • Cell Nucleus / genetics*
  • Cell Nucleus / metabolism*
  • Cloning, Molecular
  • Cytoplasm / genetics*
  • Cytoplasm / metabolism*
  • Cytoskeletal Proteins
  • DNA, Complementary / biosynthesis
  • DNA, Complementary / genetics
  • Gene Expression / genetics*
  • Gene Library
  • Germ Cells / metabolism*
  • Haploidy
  • Immunohistochemistry
  • In Situ Hybridization
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Molecular Sequence Data
  • Spermatogenesis / physiology
  • Testis / cytology
  • Testis / metabolism


  • Actins
  • Actl7a protein, mouse
  • Actl7b protein, mouse
  • Cytoskeletal Proteins
  • DNA, Complementary