GRGR(4) Pop Quiz In The Morning

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For the entire article: 
http://www.bioscience.org/1996/v1/d/baldi1/htmls/189-205.htm#2.3.3

HUMAN SPERM ACTIVATION DURING CAPACITATION AND ACROSOME REACTION: ROLE
OF CALCIUM, PROTEIN PHOSPHORYLATION AND LIPID REMODELLING PATHWAYS. 

Elisabetta Baldi, Michaela Luconi, Lorella Bonaccorsi, Csilla Krausz and
Gianni Forti. 


2.3.3. Involvement of tyrosine phosphorylation in capacitation 

The first evidence for the presence of tyrosine phosphorylated proteins
in mammalian spermatozoa dates
back to 1989 (72). Using anti-phosphotyrosine antibodies, Leyton and
Saling identified three different
phosphoproteins at 52, 75, and 95 kDa in the mouse spermatozoa (72). The
95 kDa protein was tyrosine
phosphorylated under all experimental conditions and including
interaction of spermatozoa with solubilized
ZP proteins (72). The 75 kDa and 52 kDa proteins were phosphorylated
only in capacitated spermatozoa
and may represent capacitation-specific markers (72). Later on, similar
tyrosine phosphorylation pattern
was reported in human spermatozoa (73-75). Phosphorylation on tyrosine
residues occurs during
capacitation, interaction of spermatozoa with zona proteins and with
progesterone (73-76). The increase in
tyrosine phosphorylation during capacitation is time-dependent (Fig. 2).