What is the Difference Between Alpha and Beta Tubulin?

Alpha and beta tubulin are two globular proteins that are components of microtubules, which are essential parts of the cytoskeleton in eukaryotic cells. They have similar weights and isoelectric points, but there are key differences between them:

1. Asp-254 and Lys-254: Alpha tubulin contains Asp-254 at the E-site, while beta tubulin contains Lys-254 at the N-site.
2. GTP Attachment: GTP is always attached to the alpha tubulin subunit, while at the beta tubulin subunit, GTP is exchangeable for the microfilaments to polymerize.
3. Gene Encoding: Alpha tubulins are encoded by TUBA genes, while beta tubulins are encoded by UBB genes.
4. Structure: Both alpha and beta tubulins have a similar structure consisting of beta sheets and alpha helices. Alpha tubulin has 13% alpha helices, 39% beta-sheets, and 48% random coils, while beta tubulin has 13% alpha-helices, 42% beta-sheets, and 45% random coils.

Both alpha and beta tubulins are essential for forming microtubules, which play crucial roles in various cellular functions, including structural support, intracellular transport, and DNA segregation.

Comparative Table: Alpha vs Beta Tubulin

Alpha and beta tubulin are two types of globular proteins that form the basic building block of microtubules. They share similarities in weight and isoelectric points but differ in their E-site and N-site structures. Here is a table summarizing the differences between alpha and beta tubulin:

The key difference between alpha and beta tubulin is their N-site and E-site structures. At the E-site of alpha tubulin, there is an Asp-254, while at the N-site of beta tubulin, there is a Lys-254. Additionally, GTP is always attached to alpha tubulin, whereas GTP-GDP is exchangeable at the beta tubulin.