SPACA3 is a 215 amino acid protein that participates in the fusion and adhesion of sperm and egg plasma membrane during fertilization. Identified as a novel cancer/testis antigen in hematologic malignancies, SPACA3 has the ability to elicit B-cell immune responses in patients with cancer and is considered a potential target for immunotherapy. A member of the glycosyl hydrolase 22 family which is expressed in testis, placenta and epididymis, SPACA3 exists as two alternatively spliced isoforms; SPACA3 isoform 1 is a single-pass type II membrane protein of the sperm acrosome whereas SPACA3 isoform 2 is a secreted protein.
Function:
Sperm surface membrane protein that may be involved in sperm-egg plasma membrane adhesion and fusion during fertilization. It could be a potential receptor for the egg oligosaccharide residue N-acetylglucosamine, which is present in the extracellular matrix over the egg plasma membrane. The processed form has no detectable bacteriolytic activity in vitro.
Subcellular Location:
Secreted and Cytoplasmic vesicle > secretory vesicle > acrosome membrane. Anterior acrosome in non-capacitated spermatozoa and retained in the equatorial segment and in the luminal face of both the inner and outer acrosomal membranes following capacitation and the acrosome reaction.
Tissue Specificity:
The processed form is expressed in sperm (at protein level). Expressed in testis, epididymis and placenta.
Post-translational modifications:
The processed form derives from the membrane form by proteolytic processing.
Similarity:
Belongs to the glycosyl hydrolase 22 family.
SWISS:
Q8IXA5
Gene ID:
124912
Database links:
Entrez Gene: 124912 Human
Omim: 612749 Human
SwissProt: Q8IXA5 Human
Unigene: 434112 Human
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