Objective    To confirm the formation of oligomers by different isomers of CABYR

a calcium-binding tyrosine phosphorylation-regulated protein.     Methods      Different human sperm extracts were analyzed by SDS-PAGE

2D IEF/SDS-PAGE

2D diagonal gel electrophoresis

2D blue native/SDS-PAGE and Western blotting

respectively

in native or non-reducing condition and reducing condition.      Results     The most abundant and

predominant subtype of CABYR in human sperms was CABYR-A with a 86×10

3

variant. Some variants contained both CABYR-A and CABYR-B. CABYR isomers were oligomerized by binding through disulfide bond. A 130×10

3

heterodimer was composed of a 86×10

3

CABYR-A variant and a 50×10

3

variant containing both CABYR-A and CABYR-B. A (200-220)×10

3

isomer contained 86×10

3

variant and a 50×10

3

variant

as well as a 35×10

3

variant (may containing both CABYR-A and CABYR-B) and a 30×10

3

variant (CABYR-A only).      Conclusion     CABYR isomers can form oligomers mainly by 86×10

3

and 50×10

3

variants

and form large oligomers by binding to other CABYR isomers. CABYR isomers participate in assembly and formation of supra molecular structure of fibrous sheath in human sperms.