Figure 1: Integrin beta-1 protein structure.

Introduction to Integrin beta-1

Protein Function

• Integrin beta-1 is a member of the integrins family. The integrin family contains at least 18 α and 8 β subunits that form 24 known integrins with distinct tissue distribution and overlapping ligand specificities.
• Integrins are α/β heterodimeric cell surface receptors that play a pivotal role in cell adhesion and migration, as well as in growth and survival.
• Integrins not only transmit signals to cells in response to the extracellular environment (outside-in signaling), but also sense intracellular cues to alter their interaction with the extracellular environment (inside-out signaling)).
• The β1 subfamily includes 12 distinct integrin proteins that bind to different extracellular matrix molecules. Control of extracellular integrin binding influences cell adhesion and migration, while intracellular signaling messages relayed by the β1 cytoplasmic tail help to regulate cell proliferation, cytoskeletal reorganization, and gene expression.
• Research studies have implicated β1 integrin in various activities including embryonic development, blood vessel, skin, bone, and muscle formation, as well as tumor metastasis and angiogenesis .

Protein Expression

• Integrin beta-1 isoform 1 is widely expressed.
• Integrin beta-1 isoform 2 is expressed in skin, liver, skeletal muscle, cardiac muscle, placenta, umbilical vein endothelial cells, neuroblastoma cells, lymphoma cells, hepatoma cells, and astrocytoma cells.
• Integrin beta-1 isoform 3 is expressed in non-proliferative and differentiated prostate gland epithelial cells, on the surface of erythroleukemia cells and in various hematopoietic cell lines.
• Integrin beta-1 isoforms 3 and 4 are expressed in muscle, kidney, liver, placenta, cervical epithelium, umbilical vein endothelial cells, fibroblasts cells, embryonic kidney cells, platelets, and several blood cell lines.
• Integrin beta-1 isoform 4 is selectively expressed in peripheral T cells.
• Integrin beta-1 isoform 5 is expressed specifically in striated muscle (skeletal and cardiac muscle).

Protein Localization

• Integrin beta-1 is predominantly localized to the cell membrane, sarcolemma, and cell junctions.

Figure 2: Integrin beta-1 ICC Experimental Results Image, Alexa Fluor® 647 Anti-Integrin beta 1 antibody [EPR1040Y] (ab214706). Red: Integrin beta-1, Green: Tubulin, Blue: DAPI.

Isoforms & Post-translation Modifications

• Human (P05556): Isoforms 1-5: 88-92 kDa (predicted)
• Mouse (P09055): Isoforms 1-2: 88-89 kDa (predicted)
• Rat (P49134): 88 kDa (predicted)

Post-translation Modifications:

• Acetylation, disulfide bonds, glycosylation, proteolytic cleavage, phosphorylation, Ubl binding

Tips for WB Experiment

Precautions

• Due to the presence of different isoforms and post-translational modifications of Integrin beta-1, the observed band size in WB experiments (130-150 kDa) may not correspond to the predicted size (~88 kDa). Multiple bands may appear, likely due to glycosylation modifications.
• When the detection signal is weak, try to optimize the experimental conditions, such as increasing the sample size, reducing the dilution of antibody, extending the exposure time, using hypersensitive color development solution, etc.

Positive Controls

• Whole cell lysates from HT-1080, U937, U87-MG, and A431 cells
• Human/rat spleen tissue lysate
• Mouse/rat heart and kidney tissue lysate
• Recombinant human Integrin beta-1 protein (ab114157)

Negative Control

• Whole cell lysate from HCT116 cells with human ITGB1 (CD29) knockout (ab275251)

Example Results

Figure 3: Anti-Integrin beta 1 antibody [EP1041Y] (ab52971)

Primary Antibody: Used ab52971 at a concentration of 1/1000.

Lane 1: Wild-type HAP1 cell lysate
Lane 2: Integrin beta-1 knockout HAP1 cell lysate
Lane 3: U87-MG cell lysate
Lane 4: A431 cell lysate

Predicted band size: 88 kDa

Key control points

In the experiment, in addition to paying attention to routine issues, it is also important to pay special attention to the following key control points:

Sample preparation:

1. Add a protease inhibitor cocktail to prevent degradation of target proteins.
2. Determine the protein concentration of the samples using Bradford analysis, Lowry analysis, or BCA analysis.

Transferring:

1. It is strongly recommended to stain the membrane with Ponceau S after the transfer to confirm the success of the transfer.

Antibody incubation:

1. It is not recommended to reuse antibodies and to always use fresh antibody preparations.

References

1. S Liu, D A Calderwood, M H Ginsberg. Integrin cytoplasmic domain-binding proteins. J Cell Sci. 2000 Oct;113 ( Pt 20):3563-71.
2. John D Hood, David A Cheresh. Role of integrins in cell invasion and migration. Nat Rev Cancer. 2002 Feb;2(2):91-100. doi: 10.1038/nrc727.
3. A van der Flier, A Sonnenberg. Function and interactions of integrins. Cell Tissue Res. 2001 Sep;305(3):285-98. doi: 10.1007/s004410100417.
4. C Brakebusch, R Fässler. beta 1 integrin function in vivo: adhesion, migration and more. Cancer Metastasis Rev. 2005 Sep;24(3):403-11. doi: 10.1007/s10555-005-5132-5.
5. Amel Mettouchi, Guerrino Meneguzzi. Distinct roles of beta1 integrins during angiogenesis. Eur J Cell Biol. 2006 Apr;85(3-4):243-7. doi: 10.1016/j.ejcb.2005.09.010. Epub 2005 Oct 10.