Hormone Binding Proteins

00:02 Let's talk about hormone binding proteins.

00:05 Now, before we begin this topic, hormone binding proteins, all of these are coming from where? Liver, liver, liver, liver.

00:12 How are the boards going to ask you about this? They'll talk to you about pregnancy, one thing.

00:16 Oh, yeah.

00:17 In pregnancy, tell me what is the major circulating hormone that is found.

00:23 Estrogen.

00:24 Good.

00:25 In pregnancy, what can you expect your binding protein concentration to be? Always elevated.

00:31 So, estrogen works in the liver to increase your binding proteins.

00:35 Which ones? We'll take a look at the table down below.

00:40 Begin at the very top.

00:41 Sex hormone binding globulin.

00:44 These are called globulins.

00:45 In other words, these are proteins.

00:47 Coming from where? The liver.

00:49 What's your hormone responsible for increasing your binding globulin? Estrogen.

00:54 Found when? During pregnancy.

00:57 Sex hormone binding globulin will bind to estrogen and testosterone.

01:01 Now, before I go on, there is one point that students keep mistaking here or confusing, and they get androgen binding globulin confused with sex hormone binding globulin.

01:12 The androgen-binding globulin, for example, let’s talk about the testes, I want you tell me what the inner cell of a testes is called.

01:24 Sertoli cell.

01:26 That also has a binding globulin.

01:29 That’s not the same one as this.

01:31 That’s where students keep confusing this.

01:33 So, you have an androgen binding globulin that locally binds your androgen within your Sertoli cell.

01:38 Keep that that separate from your sex hormone binding globulin.

01:41 I’m going to give you a second example where students keep getting this confused as well.

01:46 It’s a concept.

01:48 What about the next one? It’s called cortico-binding hormone.

01:50 In other words, cortisol binding hormone.

01:53 It’s cortisol.

01:54 Neurophysins, where are you? The neurophysins actually would be up in the hypothalamus responsible for binding your posterior pituitary hormones.

02:03 Take a look at vasopressin, oxytocin.

02:05 That’s all that I wish to say about that.

02:07 Now, this is the other one here.

02:09 Thyroid-binding globulin, here’s it’s the liver, estrogen will up-regulate thyroid-binding globulin.

02:14 That is a huge topic for us.

02:17 But do not confuse this with in the thyroid gland.

02:21 What is it that actually attaches to T3, T4? What attaches to T3, T4 and brings it into the colloid? Of a thyroid follicular epithelial cell into the colloid is called your thyroglobulin.

02:39 Do not confuse the thyroglobulin, which is important clinically, especially if you are using it to, let’s say, measure pathology such as papillary cancer thyroid or Hashimoto.

02:52 Then do not confuse that with our binding globulin, which is being released from the liver.

02:57 Then you have IGF-binding protein and you also have something called vitamin D binding proteins.

03:02 Take a look at all of these.

03:03 All of these particular hormones are pretty much, well, lipid soluble, aren’t they? They’re all lipid soluble.

03:09 They need to have a binding globulin, so that you properly chaperone them in your circulation.