A new Swiss army knife for immunofluorescence: Chimeric heavy chain antibodies

Posted by Klaus Herick on Feb 25, 2021 12:45:00 PM

Nanobody-Fc fusion - An alternative Nanobody format that combines its special epitope binding properties with the detection options for Fc-domains

What are heavy chain antibodies?

The immune repertoire of camelids like alpacas comprises three IgG antibody subclasses: IgG1, IgG2, and IgG3. Whereas IgG1 is a regular conventional IgG, i.e. composed of two heavy chains and two light chains, the subclasses IgG2 and IgG3 are heavy chain antibodies (HCAbs). These heavy chain only IgG antibodies differ from conventional IgGs by their hinge regions and by the absence of both the CH1 domains and light chains.

The binding domain of a heavy chain only IgG is also known as VHH or Nanobody, which has special binding properties as they tend to bind only to 3-dimensional, i.e. functional active targets with high affinity.




Why using Nanobody Fc-fusion antibodies?

Now, ChromoTek offers via Proteintech recombinant antibodies, which consist of Nanobodies as antigen binding domains with the Fc-domains of a conventional IgG antibody, or with other words chimeric heavy chain antibodies of Alpaca VHHs with Fc domains of both rabbit IgG and mouse IgG1.

Grafic 2 Fc FusionThe Fc-domain fusion format combines the advantages of Nanobodies with those of traditional antibodies: The VHH/Fc fusions (i) are bivalent so they have even higher avidities and affinities than the parent Nanobodies, (ii) bind unique, 3-dimensinal conformations of epitopes not recognized by traditional antibodies, and (iii) can be detected and captured using tools from the broad range of antibody reagents like secondary antibodies and Nano-Secondaries.


Product highlights and benefits:

  • Unique epitopes that traditional antibodies do not recognize
  • Popular nanobodies cited in over 2000 papers are fused to rabbit IgG or mouse IgG1 Fc-domains
  • Bivalent structure results in higher avidity and better signal amplification than Nanobodies
  • Detection by a broad range of secondary antibodies including Nano-Secondaries
  • Unlimited supply, high lot-to-lot consistency
  • Recombinant expression

Like other recombinant antibodies, VHH/Fc-fusions are available with high lot-to-lot consistency at an unlimited supply. The Nanobody Fc-fusion recombinant antibodies have been developed in collaboration with Absolute Antibody Ltd.


What Nanobody Fc-domain fusion recombinant antibodies are available?

Proteintech and ChromoTek offer Nanobodies fused to two different Fc-domains - rabbit IgG and mouse IgG1 – for flexibility in your experiments. The popular ChromoTek Nanobodies anti-GFP-, anti-mNeonGreen, anti-TurboGFP-, and anti-Vimentin-VHHs are all available in chimeric rabbit IgG and mouse IgG1 form. Get them here.

nfms_IF_annotated_1x4HeLa cells transiently expressing Lamin-Chromobody®-mNeonGreen were immunostained with mNeonGreen recombinant antibody, VHH-mouse IgG1 Fc fusion [CTK0203] (nfms-20, 1:500) and Nano-Secondary® alpaca anti-mouse IgG1, recombinant VHH, Alexa Fluor® 647 [CTK0103, CTK0104] (sms1AF647-1, 1:500). Scale bar, 10 μm.


vfrb_IF_annotated_1x3MDCK cells were immunostained with Vimentin recombinant antibody, VHH-rabbit IgG Fc fusion [CTK0211] (vfrb, 1:1,000) and Nano-Secondary® alpaca anti-human IgG/anti-rabbit IgG, recombinant VHH, Alexa Fluor® 647 [CTK0101, CTK0102] (srbAF647-1, 1:1,000). Scale bar, 10 μm.



ChromoTek, and Nano-Secondary are registered trademarks of ChromoTek GmbH, part of Proteintech Group. Nanobody is a registered trademark of Ablynx, a Sanofi company. Alexa Fluor is a registered trademark of Life Technologies Corporation, a part of Thermo Fisher Scientific Inc. Other suppliers’ products may be trademarks or registered trademarks of the corresponding supplier each. Statements on other suppliers’ products are given according to our best knowledge.


Topics: Immunofluorescence, VHH, Nanobody, mNeonGreen, GFP, TurboGFP, Antibody, Vimentin

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