Loading controls are used to normalize the levels of proteins detected using Western blotting, and will:

confirm that there is an equal loading across the gel
confirm that the protein transfer is even throughout the whole gel
allow qantification
can be requested by referees of scientific publications

Proteins of high levels of constitutive expression are usually recommended as loading controls. However, the choice of the appropriate house-keeping protein depends on the experiment in question, and thus needs to be confirmed. House-keeping proteins cannot be used for normalization if there is a suspicion that the experimental conditions are affecting their expression.

Agrisera's Collection of Antibodies to Loading Controls can be found here. Until end of March 2021 they are offered at 15 % off.
Mention Promocode: Loading15 when placing the order.

Agrisera Loading Controls

AS16 4111 ACT | Actin (monoclonal)
AS13 2640 ACT | Actin (polyclonal)
AS16 4111S ACT | Actin (protein)
AS03 030 AtpB | Beta subunit of ATP synthase (chloroplastic + mitochondrial) (chicken antibodies)
AS05 085 AtpB | Beta subunit of ATP synthase (chloroplastic + mitochondrial) (rabbit antibodies)
AS16 3976 AtpB | Beta subunit of ATP synthase, mitochondrial
AS07 217 FtsZ | Procaryotic cell division GTPase (cyanobacterial)
AS15 2894 GAPC1/2 | Glyceraldehyde-3-phosphate dehydrogenase
AS13 2727 GAPC2 | Glyceraldehyde-3-phosphate dehydrogenase
AS10 710A H3 | Histone H3 (affinity purified)
AS15 2855 H3 | Histone H3 (chicken antibody)
AS10 710 H3 | Histone H3 (rabbit antibody) (nuclear marker)
AS10 710-ALP H3 | Histone H3, ALP-conjugated (40 µg)
AS10 710-HRP H3 | Histone H3, HRP-conjugated (40 µg)
AS06 142-33 PsbO | 33 kDa of the oxygen evolving complex (OEC) of PSII (anti-protein)
AS08 305 PsbP | 23 kDa protein of the oxygen evolving complex (OEC) of PSII (anti-monocot protein)
AS06 142-23 PsbP | 23 kDa protein of the oxygen evolving complex (OEC) of PSII (anti-protein)
AS10 700 RA | Rubisco activase
AS01 017 RbcL | Rubisco large subunit, form I (chicken)
AS03 037 RbcL | Rubisco large subunit, form I (rabbit)
AS15 2832A RPN6 | 26S proteasome non-ATPase regulatory subunit 9
AS10 680 Tubulin alpha chain (polyclonal antibodies)
AS10 681 Tubulin beta chain