{PDOC00467}
{PS00541; TP1}
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* Nuclear transition protein 1 signature *
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In mammals, the second  stage  of  spermatogenesis  is  characterized  by  the
conversion of  nucleosomal  chromatin   to  the  compact,  nonnucleosomal  and
transcriptionally inactive form found in the sperm nucleus.  This condensation
is  associated  with  a  double-protein  transition.   The  first   transition
corresponds to the  replacement  of  histones  by  several  spermatid-specific
proteins (also called transition proteins) which  are  themselves  replaced by
protamines during the second transition.

Nuclear transition protein 1  (TP1) [1] is  one  of  these  spermatid-specific
proteins.  TP1 is a basic protein of 54 amino-acid residues  whose sequence is
well conserved in mammalian species.   As  a signature  pattern, we selected a
heptapeptide located in positions 28 to 34.   This  heptapeptide contains five
basic residues (Arg or Lys) as well as a  tyrosine that could be essential for
the destabilization of chromatin by intercalating between the bases of DNA.

-Consensus pattern: S-K-R-K-Y-R-K
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: December 1991 / First entry.

[ 1] Chirat F., Martinage A., Briand G., Kouach M., Van Dorsselaer A., Loir M.,
     Sautiere P.
     "Nuclear transition protein 1 from ram elongating spermatids. Mass
     spectrometric characterization, primary structure and phosphorylation
     sites of two variants."
     Eur. J. Biochem. 198:13-20(1991).
     PubMed=2040274

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