Background: MID1 Protein and Its Biological Role

MID1 (Midline-1), also known as TRIM18, is a member of the tripartite motif (TRIM) protein family. It contains an N-terminal RING domain with E3 ubiquitin ligase activity, two B-box zinc-finger motifs, and a coiled-coil domain. MID1 associates with microtubules and plays a critical role in regulating the degradation of the catalytic subunit of protein phosphatase 2A (PP2Ac) via the ubiquitin-proteasome pathway.

Loss-of-function mutations in the MID1 gene are causally linked to X-linked Opitz G/BBB syndrome, a congenital disorder characterized by midline developmental defects including hypertelorism, cleft palate, and hypospadias. MID1 has also been implicated in mTOR signaling, Huntingtin protein regulation, and cancer biology, making it a target of broad research interest.

Sample Preparation and Recommended Dilutions

Proper sample preparation is essential for optimal MID1 Antibody performance. Follow the guidelines below for each application:

• Western Blot (WB): Lyse cells or tissue in RIPA buffer supplemented with protease inhibitors. Separate 20–40 µg of total protein by SDS-PAGE and transfer to PVDF or nitrocellulose membrane. Block with 5% non-fat milk or BSA in TBST for 1 hour at room temperature. Incubate with MID1 Antibody at the manufacturer's recommended dilution (see product datasheet; specific dilution not stated in current source material — consult Absea #OC-2536 datasheet) overnight at 4°C.
• Immunohistochemistry (IHC): Use formalin-fixed, paraffin-embedded (FFPE) sections. Perform antigen retrieval using citrate buffer (pH 6.0) or EDTA buffer (pH 9.0). Block endogenous peroxidase activity before primary antibody incubation. Apply MID1 Antibody at the recommended dilution and incubate overnight at 4°C.
• Immunofluorescence (IF): Fix cells with 4% paraformaldehyde and permeabilize with 0.1–0.3% Triton X-100. Block with 5% normal serum for 1 hour. Incubate with MID1 Antibody at the recommended dilution for 1 hour at room temperature or overnight at 4°C, followed by appropriate fluorescently labeled secondary antibody.

Note: Specific working dilutions are provided on the product datasheet (Absea #OC-2536). Always perform a pilot titration experiment to determine the optimal dilution for your specific experimental system.

Storage, Handling, and Formulation Notes

MID1 Antibody (Ab351010) is formulated in PBS only, without carrier proteins such as BSA or glycerol, and without preservatives such as sodium azide. This formulation is particularly suitable for applications requiring conjugation or downstream functional assays where carrier proteins or preservatives may interfere.

Storage Recommendations:

• Store at -20°C for long-term storage.
• For short-term use (up to 1 month), the antibody may be stored at 4°C.
• Avoid repeated freeze-thaw cycles, which can lead to antibody aggregation and loss of activity. Aliquot the antibody upon first thaw if repeated access is anticipated.
• Do not store in frost-free freezers, which undergo temperature cycling.

Handling Tips:

• Briefly centrifuge the vial before opening to collect contents at the bottom.
• Keep on ice during use to maintain antibody integrity.
• Use low-binding microcentrifuge tubes to minimize adsorptive losses when working with diluted antibody solutions.

Troubleshooting Common Issues

The following troubleshooting guide addresses common challenges encountered when using MID1 Antibody: