CD74 · Western blot design guide

CD74 Western Blot Planning Guide

Plan a CD74 Western blot around the catalog-observed 33.5 kDa band, image-backed A01340-4 evidence, HPA controls, and verified protocol records.

Evidence assembled July 2026 · For research use; verify linked source records and product datasheet before use

Western blot protocol sheet for CD74 (CD74): expected band 33.5 kDa, antibody A01340-4, and PMC-cited SDS-PAGE protocol steps

Band Protocols Controls Antibodies

CD74 Western Blot Experimental Design Guide

Expected bands, documented protocol parameters, controls and antibodies — the at-a-glance facts below, then the full design guide.

Must know before running

	Expected band	33.5 kDa
	Observed band	Not reported — verify product WB image
	Gel	12-15%
	Positive control ⓘ	Skin
	Negative control ⓘ	Epididymis

Important caveats

Reasons your observed band may differ from the expected size.

ⓘ	Calculated mass	33.5 kDa
ⓘ	Localization	Cell membrane / Endoplasmic reticulum membrane
ⓘ	Processing / PTM	Record-dependent
ⓘ	Reactivity	Human

Sample controls for CD74 Western blot

🧪Use Skin as the first positive-control candidate and Epididymis as the HPA Not detected negative candidate.

Positive control: Skin (High)

Negative control: Epididymis (Not detected)

HPA protein score determines control status; other expression data is supporting context only.

HPA tissue expression evidence for CD74

Comprehensive Human Protein Atlas IHC scoring per tissue. Rows are taken directly from the HPA tissue chart on each tissue page — click any row's HPA link to view the source.

Positive expression · recommended positive controls

Tissue	Cell type	Level	Evidence	Source
Skin	Reported tissue cells	High	Protein (HPA)	HPA →
Cerebellum	Reported tissue cells	High	Protein (HPA)	HPA →
Appendix	Reported tissue cells	High	Protein (HPA)	HPA →
Duodenum	Reported tissue cells	High	Protein (HPA)	HPA →

Undetected expression · recommended negative controls

Tissue	Cell type	Level	Evidence	Source
Epididymis	Reported tissue cells	Not detected	Protein (HPA)	HPA →
Colon	Reported tissue cells	Not detected	Protein (HPA)	HPA →

Section 1

What Is the Expected CD74 Western Blot Band Size?

Use the product-observed 33.5 kDa band as the primary planning value and retain the UniProt calculated mass as context.

What am I looking at on my blot?
33.5 kDa	Matches the authoritative product WB observation.
33.5 kDa calculated	Use as UniProt context, not as a replacement observed band.
Unexpected additional signal	Do not assign identity without orthogonal positive/negative controls.

💡Expected CD74 appearancePlan around 33.5 kDa and keep the calculated mass as supporting context.

How each factor affects band size
Catalog-observed band	33.5 kDa; use this as the primary experimental expectation.
Calculated mass	33.5 kDa from UniProt P04233; retain as context.
Gel selection	12-15%; shared with the recommended protocol and poster.
Specificity check	Compare the lead HPA positive and negative controls with A01340-4.

Why is my band missing or off?
Situation	Likely cause	Next action
33.5 kDa	Matches the authoritative product WB observation.	Confirm with orthogonal controls and the linked product record.
Additional band	May reflect processing, modification, or non-specific signal.	Run a dilution series and compare positive/negative controls.
Weak signal	Target abundance or transfer may be limiting.	Verify transfer, increase positive-control abundance, and bracket exposure.

Sources: UniProt P04233 Human Protein Atlas product datasheet (A01340-4)

Experiment evidence

Western blot images showing CD74 band

A01340-4 · CD74 — observed 33.5 kDa WB validation

A01340-4 · CD74Observed 33.5 kDa · product-specific WB image

← swipe / scroll for more images →

Real WB data behind the band-size expectations in this section.

Section 2

Real Curated CD74 Western Blot Protocols

Start with the molecular-weight rule, then compare verified publication-derived conditions.

Recommended Western blot protocol parameters
Sample / lysate	Appendix
Gel %	12-15%
Load	20-30 µg total protein per lane
Transfer	Semi-dry, standard transfer
Membrane	0.45 µm PVDF
Blocking	5% non-fat milk or 5% BSA in TBST
Primary	A01340-4 at datasheet starting dilution
Primary incubation	Overnight at 4 °C with gentle agitation
Secondary	Species-matched HRP conjugate at validated dilution
Wash	3 × 5 min in TBST
Detection	Chemiluminescent substrate
Exposure	Bracket exposures to avoid saturation

Section 4

Advanced CD74 Western Blot Tips

Deeper troubleshooting and optimisation questions for CD74, answered from its protein features.

Which band should guide the blot?

Use 33.5 kDa, the observation attached to the authoritative A01340-4 WB record.

How should calculated mass be interpreted?

Treat the UniProt calculated mass as context; it does not replace the catalog-observed 33.5 kDa expectation.

Which positive control should I start with?

Start with Skin, the lead HPA protein-expression candidate.

Which negative control is defensible?

Use Epididymis as an orthogonal HPA Not detected candidate.

Which gel should I use?

Use 12-15% consistently across the quick facts, protocol table, and poster.

What transfer method to use for CD74 Western blot?

Use the transfer method in the recommended protocol and verify transfer before blocking.

How should A01340-4 be started?

Start at the linked datasheet condition and run a three-point primary-antibody dilution test.

Which publication-derived protocols can I compare?

Compare only the supplied target-verified records: PMC8429975, PMC11669987, PMC6436447.

Boster reagents

CD74 Western Blot Reagents

Human-reactive CD74 Western blot reagents with authoritative product imagery.

Real WB data Western blot validation image for CD74 using A01340-4; observed band 33.5 kDa

Anti-CD74 Antibody Picoband®

Cat # A01340-4

Reactivity: Human

View product →

Only image-backed, WB-validated Human/Mouse/Rat recommendations from the prepared catalog evidence are shown.

Source: prepared picoband-wb product evidence; each card retains its own SKU, URL, observed band, and authoritative WB image.