Sperm protein 17 is expressed in the sperm fibrous sheath.
BACKGROUND
Sperm protein 17 (Sp17) is a highly conserved mammalian protein characterized in rabbit, mouse, monkey, baboon, macaque, human testis and spermatozoa. mRNA encoding Sp17 has been detected in a range of murine and human somatic tissues. It was also recognized in two myeloma cell lines and in neoplastic cells from patients with multiple myeloma and ovarian carcinoma. These data all indicate that Sp17 is widely distributed in humans, expressed not only in germinal cells and in a variety of somatic tissues, but also in neoplastic cells of unrelated origin.


METHODS
Sp17 expression was analyzed by immunocytochemistry and transmission electron microscopy on spermatozoa.


RESULTS
Here, we demonstrate the ultrastructural localization of human Sp17 throughout the spermatozoa flagellar fibrous sheath, and its presence in spermatozoa during in vitro states from their ejaculation to the oocyte fertilization.


CONCLUSIONS
These findings suggest a possible role of Sp17 in regulating sperm maturation, capacitation, acrosomal reaction and interactions with the oocyte zona pellucida during the fertilization process. Further, the high degree of sequence conservation throughout its N-terminal half, and the presence of an A-kinase anchoring protein (AKAP)-binding motif within this region, suggest that Sp17 might play a regulatory role in a protein kinase A-independent AKAP complex in both germinal and somatic cells.
Chiriva-Internati
Maurizio
M
Division of Hematology & Oncology, Texas Tech University Health Sciences Center Lubbock, TX, USA. maurizio.chiriva@ttuhsc.edu
Gagliano
Nicoletta
N
Donetti
Elena
E
Costa
Francesco
F
Grizzi
Fabio
F
Franceschini
Barbara
B
Albani
Elena
E
Levi-Setti
Paolo E
PE
Gioia
Magda
M
Jenkins
Marjorie
M
Cobos
Everardo
E
Kast
W Martin
WM
D000818:Animals; D000954:Antigens, Surface / Q000235:genetics / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D013094:Spermatozoa / Q000502:physiology / Q000648:ultrastructure*; D015044:Zona Pellucida / Q000737:chemistry / Q000378:metabolism
D000954:Antigens, Surface; D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins; D008565:Membrane Proteins; C090172:SPA17 protein, human