Fairly standard "gel ran badly" result. The problem is not with your antibodies, it's with your gel.

Possible causes off the top of my head: 

1) leakage down the sides of the gel

This is where there are small gaps between the gel plates and the gel itself, and small amounts of sample squeeze down and are (obviously) not separated by size, or indeed separated at all, forming longs streaks that are then transferred to the blot.

Precast gels can do this quite often, I find, especially if they're nearing their use-by date (the gel shrinks as it ages).

2) improper sample solubilization

You don't specify how you're doing this: I assume you're not loading straight RIPA isolates, but are instead using some kind of denaturing & reducing sample buffer (plus heat, ideally), but if your samples are not properly solubilized then you'll have clumps of protein aggregates that enter the gel more slowly, producing big streaks (as shown). Similarly: proteins that have precipitated out of solution (for example, following heating without presence of suitable denaturant/reducing agent) will behave much the same.

It might be worth running a couple of gels just with coomassie staining (i.e. no transfer, just use the gel to confirm good sample separation) just to optimise your gel running conditions.

Thanks, John. I really appreciate the input!

The gels are brand new, so I don't think that's the issue, however leakage down the sides sounds like the best contender. I didn't have gel loading tips when I ran this so I'm thinking that might have had something to do with sample getting into the gaps. Loading didn't go as smoothly as usual.

I'm loading a mixture of 4X LDS sample buffer, 10X sample reducing agent, the protein lysate, and then 1X PBS to bring me to my 25microliter mark. That mix gets placed into a 37degree hot water bath for 30 minutes before loading into the wells.

I'll definitely try running with just coomassie and see what I end up with!

Good stuff. Precast gels can be very fussy at times.

37deg for 30mins sounds overly mild, but if it's worked for you in the past I wouldn't change it.

For reference, unless I'm looking at membrane proteins (in which case I don't heat at all), I generally use 95-100 degrees for three minutes.

I look at a lot of big proteins, though, so this may not be necessary for you.

Hmm that's interesting. This is the first time my lab is doing any work with tau, so I haven't quite optimized things just yet. I'll look into some sources and see what the standard seems to be. 

Hi,

If you could answer for the below it would be helpful to figure out.

1. Did you kept your gel for a longer time in transfer buffer before blotting?

2. Whats your method of blotting? [say for example Semi dry blotting]

Krishna, 

We use an Invitrogen iblot2 system so we don't use a transfer buffer. It's a dry blot system.