GnT1IP expression is regulated during spermatogenesis and enhances binding to Sertoli cells. (A) Diagram of GnT1IP cDNA and primer pairs for RT-PCR. (B and C) Total RNA from spermatocytes and spermatids partially purified from testes at postnatal day 11 (11 d) to 13 wk (13 w) was subjected to RT-PCR. Primer pair 6 detected only GnT1IP-L; pair 7 detected both GnT1IP-L and -S. Actin primers generated a 280-bp cDNA or 320-bp product from genomic DNA (*). Primer pairs 4 and 8 detected GnT1IP-L and -S coding regions. (D) Equal numbers of CHO cells stably expressing vector GFP, Myc-GnT1IP-S, HA-GnT1IP-L, or Lec1 cells labeled with CFDA-SE were assayed for binding to TM4 Sertoli cells. Images of wells after washing were taken by fluorescence microscopy (FITC channel merged with phase contrast, 10x). Bars, 40 µm. (E) Three pictures taken from fields similar to those shown in D close to the center of each well were processed by NIH ImageJ software, green cells were counted, and triplicates averaged. Error bars = SD; n = 4 experiments. **, P < 0.01; *, P < 0.05 based on the two-tailed Student’s t test. (F) Lec1 cells expressing GlcNAcT-I-HA selected for hygromycin resistance or sorted for L-PHA binding (GlcNAcT-I-HA^L-PHA) were tested for binding to TM4 Sertoli cells as in D. Bars represent range (n = 2).