Usually, venture capital firms have funds that last for 10 years, and so by and large they are immune from the mess on Wall Street. That’s good for technology start-ups, who count on VC firms to back them.

However, large financial institutions, many of them in Wall Street, are among those that provide venture capital firms their money. And if those investors get hurt, so could their commitments to the venture firms.

Take an extreme case, FTVentures{{/a}. Founded in 1998, FTVentures is a venture capital firm that invests solely into technologies that serve the financial industry.

But it also relies on 40 banks and pension funds to supply its entire capital.

In April, we reported how the firm, with offices in San Francisco and New York, finished raising a fresh $512 million in new funds from those financial investors. However, those funds weren’t deposited immediately into FTVentures’ accounts. The funds typically remain with the investors until FTVentures calls down the money, which means the funds may be evaporating in many cases as banks like Lehman Brothers and WaMu go under.

FT has now got to be sweating pretty badly, because among its investors are not only WaMu and Lehman, but other failed or struggling institutions, such as AIG, Fannie Mae, Freddie Mac, Goldman Sachs, Wachovia and National City.

Once a certain number of LPs don’t meet their calls, the fund could be endangered.

I reached the firm’s managing director Karren Gilbert for comment. She said the firm had managed to draw down a “significant” portion of the funds. She said negotiations continue with the troubled banks, and that she’s hopeful that Barclays (which bought parts of Lehman) and JP Morgan (which bought parts of WaMu) might make good on the commitments to FTVentures. She said it was too early to know the exact impact on the firm, but did say that she felt it is diversified enough — with investments from places like the State of New York — that it will do just fine. “We don’t anticipate any defaults,” she said. She provided few other details.

To some degree the fund might be cushioned by those public pension funds brought in for the new fund – but they might be in bad shape too, and unwilling to meet their calls — and quite happy to tip the balance over the line in terms of the fund needing to shut, if it came to that. Also, not all LPs invest the same amount, i.e, one bank might have invested $30 million and another only $5 million – but its hard to know whether this works for or against FT at this stage.

For now, though, the firm insists it’s not in trouble.

As for FTVentures’ own investments into companies, they include OpenSpan, Mu Sigma and Welton Street and many more.